Abstract: A feeder includes a housing, an ejection structure, and a driving module. The housing includes a discharge channel. The discharge channel has an accommodating space and a discharge port communicated with each other. The ejection structure includes an ejection blade. The ejection blade is rotatably disposed in the accommodating space. The driving module is configured to rotate the ejection structure, so that the ejection blade ejects the feed located in the accommodating space away from the discharge port. The driving module includes a position-returning member configured to maintain the ejection structure in a first rotational orientation relative to the housing. The driving module is further configured to rotate the ejection structure relative to the housing to exceed a second rotational orientation and then release the ejection structure.

Abstract: Aquarium feeding systems are disclosed. In one embodiment, a system (10) includes a flotation base (20) adapted to float on water and a clip (130) adapted to be removably inserted into and removed from the flotation base (20). The clip may hold food materials (e.g., seaweed) for feeding aquatic life of the aquarium.

Abstract: The invention is an apparatus unit that adjusts the dispersion from a compartment to an aqueous solution in response to an independent variable such as an environmental factor, in order to optimize seeding, marking, warning or treatment. The compartment enables any selection of solids, liquids or gasses to be contained and mixed when ready for dispersion. A preferred embodiment is a solar powered pump, self-contained within a buoy over a shallow tidal pool, for the purpose of distributing seeds for marine vegetation under ideal conditions for propagation. The unit provides for sensing and measurement of the environment, then adapting the dispersion for optimum effect.

Abstract: A ramped platform device for a vivarium includes a first plate that has a fastener engaged to an upper for coupling to an upper rim of a wall of the vivarium, such as an aquarium or a terrarium. The first plate is in substantial abutment to an inner face of the wall. A platform is coupled to and extends substantially perpendicularly from a lower end of the first plate. A second plate that is coupled to and which extends transversely and downwardly from a perimeter of the platform allows an animal to climb up to and down from the platform.

Abstract: Methods, systems, and apparatus, including computer programs encoded on computer-readable storage media, for automated camera positioning for feeding behavior monitoring. In some implementations, a system obtains an image of a scene from one or more cameras and a spatial model that corresponds to a subfeeder. The system determines, based on data from the spatial model and the image of the scene, a current position of the one or more cameras relative to the subfeeder. The system selects an updated position of the one or more cameras relative to the subfeeder. The system moves the one or more cameras to the updated position. In some implementations, the system dynamically selects the updated position of the one or more cameras relative to the subfeeder.

Abstract: An illumination system for cultivation of aquatic animals is disclosed for cultivation of aquatic animals in a volume of water, the cultivation using a feeding system defining a feeding axis in the volume of water. The system comprises at least a first illumination surface positioned in the volume of water and arranged for illuminating the feeding axis. The system also comprises a second illumination surface positioned in the volume of water and arranged for illuminating the feeding axis. The first illumination surface and second illumination surface are different surfaces arranged to illuminate the feeding axis from substantially different directions.

Abstract: Generating consensus feeding appetite forecasts include providing a first feeding parameter data set associated with a first feeding parameter to a first feeding appetite forecast model and providing a second feeding parameter data set associated with a second feeding parameter to a second feeding appetite forecast model different from the first forecast model. The first feeding appetite forecast model is adaptively weighted with a first weighting factor relative to a second weighting factor for the second feeding appetite forecast model. An aggregated appetite score based on a combination of the first feeding appetite forecast model using the first weight factor and the second feeding appetite forecast model using the second weight factor. Further, a feeding instruction signal based at least in part on the aggregated appetite score is provided for modifying the operations of a feed control system.

Abstract: Apparatus and methods for automatically feeding fish at predetermined intervals are disclosed herein. An automatic fish feeder can include a housing, at least one cover, a feeding track, and a valve. The housing can include a peripheral outer cover and at least one access hole. The food storage reservoir can be connected to the housing and configured to be accessible by an access hole. At least one cover can be removably attached to the peripheral outer cover and substantially seal the food storage reservoir. The feeding track can be coupleable to the food storage reservoir and configured to receive and distribute food from the food storage reservoir at individual rates. The valve can be coupleable to the feeding track and configured to control the flow of food from the feeding track. The valve can include a rod and a counter configured to move the rod relative to the feeding track.

Abstract: A chum dispenser for selectively and controllably dispending chum into a surrounding body of water is provided. Specifically, the chum dispenser includes at least one receptacle with an interior portion, defining at least two sections separated by a porous divider. The two sections include an upper chum receiving section and a lower chum dispensing section. An inlet line is fluidically connected to the chum receiving section and a fluid/water source. The inlet line is structured to provide a flow of fluid/water into the chum receiving section for mixing with the chum and creating a fluid-chum mixture. An outlet line is disposed in a fluidically communicative relation with the chum dispensing section of the receptacle in order to provide a flow of the fluid-chum mixture into the surrounding body of water. A fluid control assembly provides a selective control of the fluid-chum mixture from the chum dispensing section.

Abstract: A multi-stage rationed feeder for ornamental fish, comprising a container, a container cover assembly and a measuring cup assembly. A falling-material receiving cover of the container cover assembly is adapted to a container cover, and a buckle position is buckled into a container cover snapping slot, such that the falling-material receiving cover is rotatably mounted and connected to the container cover. The measuring cup assembly comprises a measuring cup and a blocking slice. One end of the blocking slice is provided with a sleeve hole for sheathing a blocking slice pin. A pin groove is adapted to a falling-material receiving cover pin snapped into the pin groove such that the measuring cup assembly is removably mounted and connected to the container cover assembly from below.

Abstract: A lighting assembly for enhancing the growth of aquatic life in an ecosystem and method of enhancing the growth of aquatic life in such an ecosystem. The assembly includes a vessel submerged within water of the ecosystem. A substrate is disposed within and surrounded by the vessel and provides electronics to provide a conditioned current to a plurality of light emitting diodes also contained on the substrate. The light emitting diodes emit light within the water of the ecosystem that provides for growth, not only in a larger volume of the ecosystem, but in addition enhances the growth of the aquatic life.

Abstract: An on-demand animal feed apparatus is provided comprising a receiving chamber, base tube and actuator. The receiving chamber comprises an upper section to connect to a feed supply, a lower section, and an intermediate section disposed between the upper and lower sections. A base tube is connected to the lower section of the receiving chamber and cooperates with the receiving chamber to define the feed reservoir. A lower portion of the base tube defines a discharge opening for dispensing animal feed. An actuator is disposed at least partially within the base tube and is configured to raise and lower in an axial direction in response to movement by an animal, thereby allowing the transfer of animal feed from the feed reservoir through the discharge opening. The lower section of the receiving chamber defines a relief area for the temporary displacement of animal feed when the actuator is raised or lowered.

Abstract: A method for feeding farmed fish by using au automatic feeder (20), which supplies a feed to the farmed fish in accordance with a preset feeding schedule, and a feed-demand sensor (22), which detects a demand for the feed by the farmed fish, characterized in that the feed-supply by the automatic feeder (20) is controlled on the basis of the detection results from the feed-demand sensor (22).

Abstract: A fish feeding device featuring an elongated shaft component with a first end portion formed into the shape of a helix for holding foodstuffs below the level of water in a fish tank and with a stopper component held by the shaft, keeping the shaft away from the inner walling of any panel portion of the tank and with the shaft component being bent about a vertically inclined central axis of symmetry of the shaft component for purposes of holding the invention about upper edging of the given panel portion and featured by further bends of the shaft component serving to hold the device fast in place about the exterior walling of and accordingly the panel portion of the fish tank.

Abstract: A fish food dispensing assembly includes (i) a handle member; and (ii) a perforated container that is selectively, magnetically linked to the handle member with an aquarium panel therebetween. The perforated container is configured to receive fish food therein and to dispense fish food therefrom in a liquid environment. The fish food dispensing assembly also acts as a cleaner and can be moved with respect to the aquarium in order to clean the aquarium and/or position the fish food dispensing assembly in desired locations for feeding fish within the aquarium.

Abstract: An illuminating system for illuminating a vivarium from the side panel of a vivarium using light emitting diodes. A containment ring for dispensing fish food within an aquarium. A perforated container with a lid for dispensing food within a vivarium. A brush for cleaning a vivarium. A method for soaking food in a sinking tray. A method of dispensing bait from a perforated container.

Abstract: A fish food dispensing assembly is comprised of: (A) a handle member; (B) a perforated container that is selectively magnetically linked to a handle member; and (C) a fish food containment ring configured to be magnetically linked to the perforated container and to the handle member. The perforated container is configured to receive fish food therein and is placed within the containment ring such that the fish food dispensed within the aquarium is substantially dispensed within a specific location within the aquarium. A floating containment ring orients a brush plate in convenient parallel position for convenient linking to the handle member. LEDs on the handle member provide illumination in different colors.

Abstract: An automatic, all-weather, AC-powered feeder can be used to supply feed to a fish pond, for example. The feeder does not clog and can be set to dispense an exact amount of food periodically. The feeder includes a hopper for holding food, such as a granular fish food. A power feed auger can be powered by an electric motor to carry food from the auger, down a main pipe, to a dispensing hole. Therefore, the hopper is not required to be positioned over the pond, but, instead, only the main pipe is disposed over the pond to release food from the dispensing hole.

Abstract: An aquatic feeding device includes a hollow body having an exterior wall, the exterior wall including an exterior surface defining an external shape of the feeding device and an interior surface defining an inner cavity of the feeding device. The hollow body includes an upper end and a lower end. An air tight chamber is formed within the inner cavity of the feeding device adjacent the upper end of the hollow body. A plurality of feeding apertures are formed within the exterior wall adjacent the air tight chamber. The plurality of feeding apertures are shaped and dimensioned to permit pets with access to the inner cavity of the feeding device.

Abstract: An improved animal feed dispenser is provided having a slow speed paddle wheel and a high speed distributor wheel. The high speed distributor wheel transports feed out of an opening in the device to spread it on the ground. The slow speed paddle wheel moves feed at a measured rate from a storage hopper and feeds it to the distributor wheel. A detachable mounting plate is used to attach the dispenser to a storage hopper, and is releasable therefrom without emptying the hopper of feed. The slow speed paddle wheel is formed from a material flexible enough to prevent feed jams caused by water absorption of the feed and other events.

Abstract: An aquatic feeding device includes a hollow body having an exterior wall, the exterior wall including an exterior surface defining an external shape of the feeding device and an interior surface defining an inner cavity of the feeding device. The hollow body includes an upper end and a lower end. An air tight chamber is formed within the inner cavity of the feeding device adjacent the upper end of the hollow body. A plurality of feeding apertures are formed within the exterior wall adjacent the air tight chamber. The plurality of feeding apertures are shaped and dimensioned to permit pets with access to the inner cavity of the feeding device.

Abstract: A magnetically coupled device for an aquarium wall. The device may include an inner member and an outer member. The inner member may include a main body portion and an inner magnetic or magnetically attractable element coupled to or disposed within the main body portion. The outer member may include an outer magnetic or magnetically attractable element and a polymer static cling layer. The outer magnetic or magnetically attractable element may be magnetically attracted to the inner magnetic or magnetically attractable element. The polymer static cling layer may be configured to allow the outer member to be removably attached to an outer surface of the aquarium wall. The inner member may be removably attached to an inner surface of the aquarium wall by magnetic attraction with the outer member. The device may provide, for example, a feeding point for aquatic life contained in the aquarium.

Abstract: An apparatus is provided for moving a floating or submerged marine structure. Embodiments include a track fixedly mounted near or under the waterline surface, extending from a first point to a second point for defining a path of motion of the marine structure. A riser cable has a first end movably attached to the track between the first and second points, and a second end fixedly attached to the marine structure. A trolley is attached to the first end of the riser cable between the first end and the track, and has a roller for engaging the track for distributing environmental forces of the marine structure to the track. A drive unit is attached to the marine structure (or to the trolley) for moving the marine structure (or the trolley) such that the marine structure or one end of the marine structure moves along the path of the track.

Abstract: An improved animal feed dispenser is provided having a slow speed paddle wheel and a high speed distributor wheel. The high speed distributor wheel transports feed out of an opening in the device to spread it on the ground. The slow speed paddle wheel moves feed at a measured rate from a storage hopper and feeds it to the distributor wheel. A detachable mounting plate is used to attach the dispenser to a storage hopper, and is releasable therefrom without emptying the hopper of feed. The slow speed paddle wheel is formed from a material flexible enough to prevent feed jams caused by water absorption of the feed and other events.

Abstract: Provided herein are systems and methods for producing fish lipids and/or biofuels from algae that use nutrient-?ch water derived from an upwelled water. The methods comprise harvesting the algae by a population of planktivorous organisms, such as fishes, gathering the planktivorous organisms, and extracting lipids from the organisms and/or polishing the lipids to form biofuel.

Abstract: Disclosed are fish food dispensers for aquariums, which are automatic and may be utilized to feed fish in the absence of the aquarist. The dispensers typically utilize a replaceable fish food container.

Abstract: Method and system for feeding aquatic animals. At least some of the illustrative embodiments are methods including submerging, at least partially, a chamber in a water reservoir, the chamber comprising a bladder comprising food for aquatic animals, periodically pumping water from the water reservoir into the chamber, exterting, by the pumping, a force on the bladder, and thereby dispensing the food into the water reservoir.

Abstract: A method for feeding farmed fish by using au automatic feeder (20), which supplies a feed to the farmed fish in accordance with a preset feeding schedule, and a feed-demand sensor (22), which detects a demand for the feed by the farmed fish, characterized in that the feed-supply by the automatic feeder (20) is controlled on the basis of the detection results from the feed-demand sensor (22).

Abstract: A method of feeding aquatic organisms with an artificial food. The food is in the form of microcapsules having an outer permeable polymeric shell of chitosan or alginate and an inner core of liquid food for the aquatic organism. The method involves introducing the microcapsules into an aquatic environment where they are available to be consumed by the organism. The shells of the microcapsules consist of a single polymer, the liquid food has a dry matter content comprising water-soluble, hydrolyzed proteins, peptides and amino acids, and the capsules are arranged to leak the liquid food into the aquatic environment through the shell such that at least 40% of the dry matter content remains in the capsules once the leakage has substantially ceased.

Abstract: An apparatus for storing, grinding, and dispensing flake style fish feed for the purpose of feeding fish in an a aquarium. The apparatus having an upper hopper for receiving a quantity of flake fish feed, a grinding mechanism in the lower portion of the upper hopper for breaking down the larger feed flakes into smaller, more uniform flakes.

Abstract: A magnetically coupled device for an aquarium wall. The device may include an inner member and an outer member. The inner member may include a main body portion and an inner magnetic or magnetically attractable element coupled to or disposed within the main body portion. The outer member may include an outer magnetic or magnetically attractable element and a polymer static cling layer. The outer magnetic or magnetically attractable element may be magnetically attracted to the inner magnetic or magnetically attractable element. The polymer static cling layer may be configured to allow the outer member to be removably attached to an outer surface of the aquarium wall. The inner member may be removably attached to an inner surface of the aquarium wall by magnetic attraction with the outer member. The device may provide, for example, a feeding point for aquatic life contained in the aquarium.

Abstract: A food dispenser (10) with particular application to delivering a controlled amount of food material (11) in particulate or powdered form to fish and other aquatic animals, and also a method of delivery of such material. The food dispenser comprises a receptacle (12) for holding the food material and shutter means (14) located at a lower end of the receptacle. In its open position, the shutter provides a passageway (16) from the receptacle past the shutter for delivery of the food material. A dispersing unit (50) supplies an air flow for dispersing the food material. A flexible mounting bracket (60) enables vibration of the dispenser during operation to assist the flow of the food material.

Abstract: A feeder for feeding bulk material into a high pressure conveying line. The feed assembly comprises a rotary feeder that has a material inlet for receiving bulk material from a low pressure source and a material outlet for discharging the bulk material into a higher pressure conveying line which is a source of leakage gas into the rotary feeder. The feeder has venting means to vent leakage gas through the material inlet without such leakage gas contacting the bulk material entering the feeder.

Abstract: A temperature measuring, algae cleaning and feeding system which includes a thermometer mounted on one side of a first support, At least one first magnet is mounted on an opposite side of the first support. The opposite side of the first support is adapted to engage the outer surface of a first wall of the aquarium. At least one second magnet is mounted on one side of the second support. A scrub pad for removing algae is mounted on the one side of the second support, the opposite side of the second support being adapted to engage the inner surface of the first wall of the aquarium opposite the first support such that the first and second magnetic means attract each other to thereby attach the first and second supports to the first wall of the aquarium. A fish feeding dispenser is mounted on the opposite side of the second support.

Abstract: Method and system for feeding aquatic animals. At least some of the illustrative embodiments are methods including submerging, at least partially, a chamber in a water reservoir, the chamber comprising a bladder comprising food for aquatic animals, periodically pumping water from the water reservoir into the chamber, exterting, by the pumping, a force on the bladder, and thereby dispensing the food into the water reservoir.

Abstract: A digital, automatic feeder for aquarium and pond animals for positioning above an aquarium tank or pond for distributing a pre-measured amount of feed into the tank or pond on a pre-determined schedule. The feeder includes a digital system and display that allows users to input either a schedule of feed amounts and days/dates, or input a variety of tank conditions and allow the system to select an appropriate schedule and amounts of food.

Abstract: The present invention discloses a feeding apparatus connectable to several feeding ducts and includes a first turntable, a fixing plate and a second turntable under a storage bin. The bottom of the storage bin is fixed to the fixing plate, and has several discharge holes, and the first and second turntables can be rotated synchronously, and several outlet holes are built corresponding to the discharge holes. When the first and second turntable are rotated, the positions of the discharge holes and the outlet holes interlaced and superimposed intermittently, so that the feed stored in the storage bin can be dropped intermittently. With a feeding air current, the feed is delivered to the outside in a high speed from each feeding duct, such that each feeding duct can distribute the feed to several feeding points, and the feeding apparatus is particularly suitable for an aquatic farm with high-density breeding tanks.

Abstract: The present invention relates to an interactive device comprising (a) a container with an object and water and (b) interactive equipment which causes interaction between (i) the object and a user or (ii) the object and other objects via the user's movements or driving by a sensor.

Abstract: A device for dispensing and distributing food for aquatic fauna, which can be fitted in aquariums or containers for holding live fish, but also in tanks for turtles and terrariums in general or similar, this device comprising a tank and means for pushing the food towards an outlet, in which the tank (11) is positioned in a substantially horizontal direction and houses a pusher-mixer (12 which occupies the internal space of the tank and consists of a shaft (17), equipped with a plurality of sloping blades (18) all facing in the same direction as the direction in which the food is pushed towards the dispensing outlet (13), and in which this dispensing outlet (13) presents a substantially vertical opening for the discharge of the food in a horizontal direction.

Abstract: The present invention discloses a feeding apparatus connectable to several feeding ducts and includes a first turntable, a fixing plate and a second turntable under a storage bin. The bottom of the storage bin is fixed to the fixing plate, and has several discharge holes, and the first and second turntables can be rotated synchronously, and several outlet holes are built corresponding to the discharge holes. When the first and second turntable are rotated, the positions of the discharge holes and the outlet holes interlaced and superimposed intermittently, so that the feed stored in the storage bin can be dropped intermittently. With a feeding air current, the feed is delivered to the outside in a high speed from each feeding duct, such that each feeding duct can distribute the feed to several feeding points, and the feeding apparatus is particularly suitable for an aquatic farm with high-density breeding tanks.

Abstract: The present invention provides for an apparatus for dispensing a slurry feed suitable for fish under the surface of an aqueous body, the apparatus comprising a housing having a feed inlet and radial feed dispensing means, means for providing a slurry containing a feed product to the feed inlet means in the housing and a radial feed dispensing means comprising a plurality of spaced-apart slurry dispensing outlets therein for dispensing slurry radially and outwardly from the housing under the water surface.

Abstract: A two-way feeder for use in an aquarium. The feeder has a base that can be buried in sand or crushed coral in an aquarium. One or more fittings on the underside of the base provides a user of the feeder with the option of applying one or more suction cups to the feeder. The suction cups are used to attach the feeder in different surfaces of the aquarium, including the bottom surface and the side walls. The feeder can be used as to attach food in at least two ways. First, buoyant foods such as cucumber can be secured to the top of the device by screwing the cucumber over the head of the threaded receiver. Second, leafy foods such as lettuce or seaweed can be secured by a spring clip associated with an adapter that is compatible with and screwed onto the threaded receiver.

Abstract: An improved feed dispenser is programmable to allow for a desired feeding schedule. When a feeding interval begins, a dispersion wheel begins operating. A separate spinner plate is used to block feed from the dispersion wheel, and begins operating to allow feed to the dispersion wheel only after a delay of several seconds after the dispersion wheel begins operation. In addition, the dispersion wheel is operated for another period of several seconds after the spinner plate ceases operation in order to clear the mechanism and prevent blockage.

Abstract: An automatic aquarium feeder apparatus including a body unit having a platform element; a platform wall on the platform element defining a cavity; a clamping mechanism for clamping the platform element to the walls of an aquarium; a drive mechanism including a battery-powered motor; and a food dispensing element having one or more first slots through the platform element, and a disk element rotatably driven by the motor and having one or more second slots that are alignable with the one or more first slots. Food in the cavity gravitationally drops through the first and second slots when aligned. The drive mechanism may include an alternating power on/power off timing mechanism.

Abstract: The invention relates to methods, compositions and kits for improving the raising of pre-adult anadromous fish, or preparing pre-adult anadromous fish for transfer to seawater. The methods involve adding at least one Polyvalent Cation Sensing Receptor (PVCR) modulator to the freshwater in an amount sufficient to increase expression and/or sensitivity of at least one PVCR; and adding feed for fish consumption to the freshwater, wherein the feed comprises an amount of NaCl sufficient to contribute to a significantly increased level of the PVCR modulator in serum of the pre-adult anadromous fish.

Abstract: A feed trough is provided for use in cultivation containers for growing frogs and other amphibians. The feed trough is comprised of a sloped floor. In some embodiments the floor slopes downward to an opening from which, during operation, airflows. The opening is covered by a perforated cover that retains the feed particles collected from the sloped floor and provides sufficient opening for airflow that propels the feed particles from the perforated cover into the airspace of the cultivation container. During operation, airflow passes through the opening with sufficient force to suspend in the air feed particles that have rolled along the sloped floor, or fallen, onto the perforated cover covering the opening. The movement of the feed particles in the air stimulates feeding by the frogs or other amphibians. Feed that is not consumed falls onto the sloped floor, rolls onto the screen or wire mesh covering the opening, and is resuspended by the airflow.

Abstract: This invention provides an in-tank dispenser for feeder fish and other aquatic live food that provides a separate enclosure residing within the larger main tank in a manner that allows the main tank's conditioned and heated water to flow through the enclosure. Feeder fish reside within the enclosure, allowing them the benefit of the main tank's filtered and conditioned water while separating them from the larger fish of the main tank until feeding time. At feeding time, a manually or automatically operated door is opened, allowing the feeder fish to access a funnel shaped outlet that is large enough for the feeder fish to pass therethrough, but small enough to restrict return of the feeder fish once they exit or to allow larger fish to enter the enclosure. The door can be perforated, and can be flapped opened and closed to help urge feeder fish into the area of the funnel. The enclosure can, likewise, be perforated to allow passage of water therethrough.

Abstract: A method of rearing aquatic species is provided, comprising feeding the aquatic species during at least part of the larval and/or post-larval state with prey organisms, such as Artemia or rotifers, having in their total lipid content a DHA content of at least 12 wt %. The method is suitable for the rearing of fish species such as halibut, turbot, bass, bream and flounder. The total lipid content of the prey organisms further including highly unsaturated fatty acids comprising 18:3, 18:4, 20:4, 20:5 (EPA) and 22:5 fatty acids. Also the prey organisms include 5 to 35 wt % phospholipids of the total lipid content, wherein the total lipid content is at least 20 wt % on a dry weight basis.

Abstract: An automatic fish feeding apparatus includes a housing that has a bottom wall and a peripheral wall. The bottom wall has a feed opening extending therethrough. A funnel is mounted in the housing. The funnel has pour opening therein that is unaligned with the feed opening. A conveyor belt assembly is mounted within the housing and positioned beneath the pour opening. The conveyor belt assembly includes a conveyor belt extending over the feed opening. A motor is mechanically coupled to the conveyor belt assembly for selectively rotating the conveyor belt in first direction such that an upper portion of the conveyor belt moves toward the front wall. Fish food may be positioned in the funnel such that the fish food is positioned onto the upper portion of the conveyor belt. The fish food falls through the feed opening when the conveyor belt is rotated. A control actuates the motor.

Abstract: Food dispensing apparatus minimizes the likelihood that food particles dispensed into an aquarium will contaminate the water filtration system or will stick to the sides of the aquarium. The food dispensing system suspends a hollow food dispensing member in water in the aquarium such that the food dispensing member guides food to the bottom of the aquarium free from being transported by prevailing currents in the aquarium.