The water in a blackwater biotope is slow moving, tea colored, acidic and soft. The goal for a blackwater aquarium is to simulate a natural stream environment for angelfish and their tank mates. Nature produces blackwater streams when leaves, wood and other vegetation have fallen into the stream. Peat moss in an aquarium can produce a blackwater habitat. The tank may also have bogwood, driftwood or Mopani wood in it that produces tannins to color water or a commercial extract can be used. Blackwater streams are found worldwide, so fish living in this environment come from different parts of the world and many can be kept with your angelfish.
Blackwater streams are those with significant amounts of wood or dead leaves in them, which release tannins in the water that turns the stream a brown color. Fish living in these slow moving streams are suitable to keep in a blackwater tank. Fish from the Asian or South American streams are popular with aquarium hobbyists, and benefit from living in a blackwater tank by enhancing their colors.
South American Blackwater Fish
Because the streams are slow moving, fish from these streams are rather sedate. Discus, angelfish, dwarf cichlids, tetras, hatchetfish, corydoas, farlowella, and loricarids are fish which live together in nature. These fish will breed and have more offspring in a blackwater environment. A blackwater tank will show fish, such as neons, in their natural vibrant color.
Even though fish are from the same area, they may not do well in a blackwater tank. For example, Central American livebearers may not do well in soft water. They tend to get fin rot and fungal infections in such conditions. Piranha are also South American fish from blackwater streams, but too aggressive to be kept with other fish.
Asian Blackwater Aquarium Fish
Barbs, danios, red tail sharks, knifefish, gourmais, glass catfish, Asian clown and dwarf loaches, wild betas and paradise fish are examples of fish for an Asian blackwater tank.
Mixing Regional Fish
Some Asian varieties will live with South American fish and vice versa. Most gourmis are quiet peaceful fish, and the smaller varieties make good tank mates with other peaceful blackwater fish such as angelfish. As with any fish some individuals may be more aggressive and cause trouble and destruction in the tank. Blue and gold gouramis can be too aggressive for an angelfish tank.
Blackwater tanks require frequent monitoring and water changes. This is needed to control the soft water and acid pH. Small water changes won’t shift the pH rapidly and less likely to cause stress to the fish. Blackwater tanks are attractive, but require more work and maintenance to keep the occupants happy and healthy. The hobbyist will have to decide if the work is worth it to maintain a blackwater aquarium.