Facts on Tropical Freshwater Fish

Tropical freshwater fish are fish kept in freshwater aquariums as pets or as a hobby. There are a number of different fish species that fall into this broad category for hobby fish keeping purposes. Forty percent of all fish species are freshwater species despite the fact that less than .01 percent of the water on the earth is fresh water.

  1. Air Bladders

    • Most tropical fish have an air bladder that helps to keep them buoyant in the water. The air bladder allows them to remain at a steady depth in the water so that they can focus on swimming forward. Some fish do not have this air bladder, requiring them to swim continually if they want to stay afloat, otherwise they float to the bottom and have to move along the floor of the aquarium. Fish can also suffer from swim bladder disease, preventing their swim bladder from regulating their depth in the water.

    Popularity

    • Tropical fish have become one of the most popular household pets in the United States. Most of the tropical fish that are sold as pets in the United States are harvested wild in other countries including Asia, Africa, South America and Central America. Tropical fish are not domesticated like dogs, cats and other household pets.

    Pain and Stress

    • Freshwater tropical fish can experience pain and undergo periods of stress just like birds and mammals can. One of the most interesting effects of a fish experiencing stress is that they can lose their colors and become dull when they are stressed out. Stressed or sick fish may stop eating, which can cause other problems over time. Despite their popularity, 95 percent of all mortality in freshwater tropical fish results from improper nutrition and housing.

    Sociability

    • Tropical freshwater fish are categorized by their social nature when kept as pets. Community tropical fish are sociable, get along well in groups and generally work well with other similar community species. Semi-aggressive tropical fish can be territorial or may pick on smaller fish but are generally not harmful in a community freshwater aquarium. Aggressive species like cichlids are outwardly aggressive and may attack fish of the same size or smaller over food and territory, making them less ideal for a multi-species aquarium.

    Size

    • The smallest tropical freshwater fish is the Philippine goby, which is less than 1/3 inch when it is fully grown. Tropical freshwater fish kept in an aquarium can continue to grow until they are too large for their aquarium. The plecostamus, for example, can grow to reach 12 inches, despite commonly being kept in a 10-gallon aquarium. The sizes of tropical fish in freshwater environments can vary significantly, so it is important to research the full-grown size of a species before introducing it to an aquarium.