A little about Lake Malawi
Lake Malawi is often quoted as containing hard alkaline water. This isn't so, the water in Lake Malawi is relatively soft when compared with other large lakes in the African Rift Valley.
The difference in pH is accounted for by differing levels of CO2 found in the water. Deeper water and sheltered bays may have higher levels of CO2 and so the pH will be lower. Wind swept shallow water will have a better gas transfer at the surface and so will contain less CO2 making the pH higher.
Lake Malawi contains approx only one third of of the dissolved mineral level of nearby Lake Tanganyika and so chemically the two lakes are very different and this is one reason why it is a bad idea to keep fish from the two different lakes in one aquarium.
Dimidiochromis: Greek, di = two + Latin, midio, dimidiatus = divided into halves, 1623 + Greek
Dimidiochromis compressiceps prefers a tank with open spaces, a sandy substrate and a thicket or two of Vallis to lurk in. One or two large flattish stones should be used which the fish will probably use to spawn over. Dimidiochromis compressiceps are quite active fish and need large open areas for swimming. Keep these fish in a group with a single male and three or four females. This will keep the male from pestering a single female to much.
Dimidiochromis compressiceps is an ambush predator which feeds on smaller fish which it lays in wait for. Aquarium specimens will accept dead 'prey' with a minimum of fuss. Lance fish, prawns, blood worms, small or chopped earth worms and shell fish all make suitable items for its diet.
Dimidiochromis compressiceps is not one of the Mbuna and does not belong in a Mbuna set up, it is a predator which prefers more open water or to lurk in a thicket of vallis. Small Mbuna WILL be eaten by this fish when it becomes an adult. More suitable tank mates are the larger 'Malawi Haps' such as , Aulonocara, Copadichromis, Cyrtocara, Fossochromis and Nimbochromis. With the right tank mates Dimidiochromis compressiceps is generally quite peaceful especially when kept well fed. But this all changes when spawning, males will claim a territory and try to exclude all other fish from their territory. Any community tank will have to be large enough to accommodate this behaviour and allow other fish to escape or they may get injured or killed.
Adult males are blue, females remain silvery. The males when adult are considerably larger than adult female.
Being cichlids Dimidiochromis compressiceps will breed if kept in good condition and there is a pair present, I have even seen them spawning in a fish store. Dimidiochromis compressiceps is a mouth brooder, the fertilised eggs are picked up by the female and kept in a brood pouch in her mouth until they hatch and the fry are ready for free swimming. The whole process will take three to four weeks depending on the temperature. During brooding the female will not eat and can be more easily bullied so it is essential that several good hiding places and refuges are provided. If kept in a community tank where other Dimidiochromis compressiceps are present it isn't a good idea to remove the female for an extended period because she will be treated as an intruder upon her return and could be injured. It is better to leave her in the original aquarium right up until a few days before the fry are ready to be 'born' and then transfer her to a tank of her own.
There is a trend of stripping the eggs from the mouth of the female and raising them artificially. My own personal opinion of the practice is that it is pointless and possibly cruel. Dimidiochromis compressiceps females have been brooding there eggs for tens of thousands of years and in that time they have become quite good at it, a lot better than we are on the whole!!!
The IUCN Red List of endangered species lists this fish as 'Least Concern'. One potential threat comes from the aquatic trade and the fish being over collected. The wild population trend is unknown.
The common name of eye biter may give rise to concern and although the eyes of other species have been found in gut samples taken from wild fish the act of a fish being attacked and its eyes removed has never been witnessed in wild fish. There are some sketchy reports about this happening in the aquaria but a well fed aquarium specimen is most unlikely to do this and the species has been successfully kept with suitable fish many times with no problem.
H: 7.6 - 8.4
dGH: 7.8 - 8.5
Temperature: 23 - 28°C (74 - 82°F)
Size: 23cm (9in)
Min tank size: 450 litres
Difficulty level: Intermediate
Aquarium type: Community
Swimming level: All levels
Origin: E Africa, Lake Malawi, the Upper Shire River and Lake Malombe(endemic)
Habitat: Shallow water with a good plant cover and occasionally in rocky areas..
Species: D. compressiceps, (Boulenger, 1908)
Common name: Malawi eye biter.