We don't often worry about the mental state of a fish, but fishes enjoy stimulation and something to do, just as much as land animals. Aquarists know that the environment is important for keeping fish in good health or bringing them into breeding condition. That doesn't just mean places to hide and clean water to swim in; it can also mean a variety of foods including live food to chase, the right tank mates, the right plants, and, yes, an opportunity to learn.

Watch Karen clicker train an Oscar! [1]

You can train a fish—any fish—just as you would clicker [1] train any pet. A famed behavioral scientist, the late Ogden Lindsley, provided KPCT with wonderful instructions on how to train a fish [1].

Use a flashlight blink for the click; and very small, highly-palatable food treats. Soft food can be squeezed in through a syringe; or drop tiny pellets such as the pelletized food that is sold for bettas. Train your guppy or goldfish to swim through a hoop, follow a target [1] on the glass, go in and out of the castle in its tank, or jump over a matchstick. (Be careful with jumping; keep the tank covered when you're not around.)

As the American Association of Zoo Keepers notes, "It is believed that enrichment can be effective for fishes if it is done to accentuate and stimulate natural behaviors. By providing animals with unpredictable changes to their environment that encourage these behaviors, aquarists can better replicate the fishes' lives as they would be in the wild." The According to the American Association of Zoo Keepers offers the following suggestions for "fish enrichment."

Enrichment Examples

The following summarizes enrichment items that may be appropriate for fishes.

Exhibit/Novel Enrichment

• Periodic changes of lighting intensity
• Seasonal change of lighting photoperiod
• Periodic changes to exhibit décor (changing logs, plants, branches, etc.)
• Random Addition of novel items (shells, rocks, leaves, plants, etc.)

Dietary Enrichment

• Feedings at different times of day
• Feedings at different places in tank (if possible)
• Creation of currents during feedings
• Creation of feeders such as film canisters with holes for brine shrimp to swim out of
• Sinking feeders—PVC pipe capped on each end or plastic ball with holes in it to allow for foraging

Social Enrichment

• Mixed species exhibits to encourage positive interspecies interactions
• Animals of the same species housed with same to encourage species-specific behaviors

Training

• Conditioning "station" behavior [1] to successfully feed animals in large mixed species exhibits
• Conditioning animals to shift from one tank to another
• Conditioning animals to change swimming patterns
• Conditioning fish to target or to push paddles for food in order to station them for examination
• Conditioning large sharks and other fish to swim into a stretcher for blood sampling or examination

Safety Considerations

There are a few safety considerations when using enrichment for fishes.

• Enrichment items should be the large enough that they can not be ingested by any of the animals in the tank
• Enrichment items should be durable enough so that they cannot be pulled apart and ingested
• It is important to ensure that animals cannot become entrapped or entangled in enrichment items
• Enrichment items should not contain materials that are toxic to fishes (i.e., ingesting, leaching chemicals into the water)
• All enrichment items should be disinfected prior to or after each use

Fishes enrichment guidelines from the American Association of Zoo Keepers compiled by Jill Forsbacka, Aquarist, and Sue Hunter, Assistant Curator of Marine Mammals, National Aquarium in Baltimore . Reprinted from the website of the American Association of Zoo Keepers [2].