Freshwater fishes of the Caribbean Islands:

March 23, 2010. Earlier today I stumbled across a post on one of the many online fishkeeping forums where an aquarist asked if there were any small freshwater fish from the Caribbean islands that would be suitable for a community aquarium. Only one person had replied, stating that only saltwater fish were found in the Caribbean. This, of course, is incorrect. In fact, one of the most popular species of aquarium fish is native to several of the islands (as well as mainland South America). If you haven’t already guessed, that fish is Poecilia reticulata, also known as the guppy. It is probably the guppy’s adaptability and preference for alkaline environments (a trait common to most poeciliids) that has allowed it to disperse across the Caribean. Poeciliids, as members of the cyprinodonts, are believed to be a secondary freshwater fish family – in other words, their ancestors were originally marine and they adapted to colonize freshwater environments. This includes another group of livebearers, the limias (pic of Limia perugiae, upper right).Unfortunately you will probably not find these at your local fish store, but there are dedicated breeders maintaining populations of these fish out there. The cyprinodonts also include the killifish, and these are also represented on the islands. One example, Cubanichthys pengelleyi or the Jamaican Large-Scaled Killie, is an absolutely striking fish.
And cyprinodonts are not the only secondary freshwater fish family. Cichlids are another group that share this distinction, and they are represented on the islands as well. For example, Nandopsis haitiensis, or the Haitian Cichlid, has colonized the island of Hispaniola. Another related species, Nandopsis tetracanthus, is found on Cuba. These cichlids are large (20-22 cm SL depending on the species) and, from what I’ve read, a bit scrappy (I believe the word “homicidal” was used to describe different species from this group of cichlids more than once, and the Haitian Cichlid is sometimes referred to as the “Black Nasty”). Both the Haitian Cichlid and the Cuban Cichlid inhabit freshwater and brackish environments, though ideally I suspect that they would prefer a lightly brackish (SG 1.005 or less) environment. Salinity is probably less important than maintaining a slightly alkaline pH. If you do decide to purchase one of these beautiful fish, be responsible and do your research!
It is unfortunate that people are not as familiar with these amazing fish found literally right next door. The Caribbean islands are of particular interest to the brackish aquarist due to the fact their isolation increases the odds that a marine fish family will take advantage of the open niche and colonize the available freshwater environments (Agonostomus monticola, the Mountain Mullet, is another excellent example). These colonizers are typically either adaptable to brackish waters or, given their ancestry, naturally inhabit brackish environments. Makes me wonder what else is out there!

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