As a group, the Cichlidae are characterised by a relatively high tolerance for salt. Most hardy cichlids, such as acara and kribs, will adapt to the low levels of salt (SG 1.003-1.005) required for things like mollies and knight gobies. The ones that will not adapt to such low-salinity brackish water conditions are chiefly those species either adapted to soft and acidic environments (such as angelfish) or the Great Lakes of the African Rift Valley (such as mbuna). Continual exposure to brackish water places a strain on the osmoregulatory systems of these specialist fish, and has been associated by some aquarists with problems such as Malawi Bloat.
No cichlid is exclusively marine, but several species are found exclusively or primarily in brackish water environments, particularly mangrove swamps, coastal lagoons, and estuaries. These tend to be highly adaptable fish and are not fussy about the precise conditions. Sarotherodon melanotheron, for example, is almost always found in brackish water in the wild, but does perfectly well in a freshwater aquarium. The chromides,
Etroplus maculatus and
E. suratensis, are exceptional in not doing well in freshwater aquaria and must be kept in brackish water.
Not all cichlids make good community fish, and reference to an aquarium book for details of size, diet, and social behaviour is recommended. On the other hand, their bright colours and intelligence does make them worthy additions to the brackish water aquarium.
Green chromides (
Etroplus suratensis), tilapias such as Sarotherodon melanotheron, and the more placid Central Americans like Cichlasoma urophthalmus make the best bets when stocking large community tanks alongside shark catfish, monos, scats, etc. Orange chromides (
Etroplus maculatus) and kribs
(Pelvicachromis spp.) generally work well in medium-sized communities with things like glassfish, mollies, knight gobies, and other non-aggressive but not too shy tankmates.
The following is a partial list of cichlids known to enter brackish water in the wild. Not all species are widely traded.
Levant, South Asia and Madagascar
- Etroplus maculatus (not less than SG 1.005, and up to SG 1.010)
- Etroplus suratensis (not less than SG 1.005, and up to SG 1.010)
- Iranocichla spp. (low salinity, <SG 1.005)
- Paretroplus damii (low salinity, <SG 1.005)
- Ptychochromis oligacanthus (low salinity, <SG 1.005)
Africa
- Hemichromis bimaculatus (low salinity, <SG 1.005)
- Hemichromis letourneuxi (low salinity, <SG 1.005)
- Oreochromis aureus (at least SG 1.010)
- Oreochromis mossambicus (up to full-strength seawater)
- Oreochromis niloticus (at least SG 1.010
- Pelviachromis pulcher (low salinity, <SG 1.005)
- Pelviachromis ocellatus (low salinity, <SG 1.005)
- Sarotherodon galilaeus (at least SG 1.010)
- Sarotherodon melanotheron (up to full-strength seawater)
- Tilapia guineensis (up to full-strength seawater)
- Tilapia rendalli (at least SG 1.010)
- Tilapia zillii (up to full-strength seawater)
- Tylochromis jentinki (low salinity, <SG 1.005)
South and Central America
- Amphilophus hogaboomorum (low salinity, <SG 1.005)
- Cichla ocellaris (low salinity, <SG 1.005)
- Cichlasoma beani (low salinity, <SG 1.005)
- Cichlasoma urophthalmus (up to full-strength seawater)
- Geophagus brasiliensis (low salinity, <SG 1.005)
- Herichthys carpintis (at least SG 1.010)
- Herichthys pantostictus (low salinity, <SG 1.005)
- Herichthys pearsei (at least SG 1.010)
- Heros severus (lowsalinity, <SG 1.005)
- Nandopsis haitiensis (up to full-strength seawater)
- Nandopsis tetracanthus (up to full-strength seawater)
- Parachromis friedrichsthalii (low salinity, <SG 1.005)
- Parachromis motaguensis (low salinity, <SG 1.005)
- Vieja maculicauda (at least SG 1.010)
- Vieja synspila (low salinity, <SG 1.005)
