If you are a looking to build a fishing habitat that will promote healthy, successful fish, you may find yourself asking some odd questions about your task. “What do fish really want?” you may wonder. “What do I need to provide local species to help them be successful?” Unfortunately, there is little information available on how to build a pond for happy fish. However, thanks to a number of research projects, that may soon change: increasingly, scientists around the world are taking an interest in the mental stimulation fish need to help them thrive.
While most people likely believe fish are creatures that lack intelligence and memory, among other things, research shows that fish are much smarter and more complex than we have originally assumed. Scientists have demonstrated that fish make friends, forge alliances, use tools, and store information for several days, all traits of “higher” species. Many experts have speculated that this evidence may explain why so many fish raised in hatcheries do not survive when they are released into the wild to bolster native populations: quite simply, they have not learned the basic life skills or cognitive abilities they need to survive.
To test this hypothesis, a number of biologists and ecologists have begun making changes to fishery environments. For example, researchers at the University of Bergen in Norway tried adding fish attractors, such as rocks and plastic plants, to their tanks, instead of raising fish in bare enclosures. Studies showed that these fish performed better in memory tests than the typical hatchery fish. Similarly, the Finnish Game and Fisheries Research Institute tried imitating natural river environments by varying water levels and introducing evidence of predators. This forces the fish to hunt for their food and protect themselves instead of lazily swimming and eating. The approach has had a startling impact on the hatchery: their fish are more evenly-sized, have lower parasite levels, and are less likely to succumb to diseases.
Despite the success of these studies, however, many of these changes are difficult to implement in a fishery setting. The use of fish attractors, for example, make tanks difficult to clean, which in turn encourages bacteria growth. Likewise, introducing stressors, even natural ones, encourages fish to focus on hiding rather than eating, making them smaller and more vulnerable to predators upon their release. As a result, researchers are constantly looking for alternatives, like artificial fish attractors, which are easier and cheaper to clean. At least one fishery is currently awaiting results from these changes after releasing 10,000 juvenile salmon into a Norwegian river.
While the ecological community awaits further data, however, those interested in building a fish habitat can benefit from the information that has been revealed. It is now clearer than ever that fish need entertainment and variety to grow healthy and strong. Whether you choose to add fish attractors or focus on cultivating a diverse population, make sure to consider what will help your fish thrive both physically and mentally.