Is there any way to get the look and feel of a saltwater aquarium with a freshwater species? Are there any freshwater fish that are colorful like saltwater fish or marine fish that can live in freshwater? I want something colorful with rock, but I don’t want to deal with mixing saltwater for water changes.
Actually, there are some fish that can live in both marine environments and freshwater. Mollies, being the most common, won’t give you the colorful appearance you are striving for. Some killifish species tolerate brackish waters and freshwater also. But killifish also won’t have the look or effect that you would like.
Freshwater fish that are colorful and unique are African cichlids from either Lake Malawi or Lake Tanganyika. Because African cichlids prefer water with a high pH and dissolved mineral content, the same substrate and rock work that is used in a saltwater aquarium would suit these fish just fine. Many people prefer crushed coral or aragonite sand as a substrate and use either base rock or moon rock to aquascape the aquarium. This creates a highly unique look that is very similar to a marine aquarium. The substrate and rock will help also help to buffer the water’s pH.
Most African cichlids prefer a water pH of 8.5 or higher. I have been most successful with a pH around 8.0 or slightly higher. To safely maintain this pH, you will need to use an aragonite substrate and a dense base rock similar to what is used in reef aquariums. That way you can naturally maintain the high pH that cichlids prefer.
While an African cichlid aquarium does create a bright and showy aquarium there is one thing to strongly keep an eye on: aggression. African cichlids from both lakes are often highly territorial and aggressive. Even though these fish are hardy, the stress from aggression can cause fish deaths if highly dominant species are kept in close quarters.
Another area of concern is mixing fish from the two different lakes. Aquarium purists striving for a natural system would never mix the different species. However, some aquarists do mix species from the two lakes together and in most cases this can be successful. In my experience the fish from Lake Tanganyika are far more docile than those from Lake Malawi.
All in all, African cichlids make for vibrant, colorful displays and are very active fish. When I had a large African cichlid aquarium people would often ask whether the aquarium was salt or freshwater.