Aphyosemion exiguum

APHYOSEMION EXIGUUM  (Boulenger 1911)     

Originally published as: B.K.A. Information Pamphlet No.54   January 1970

Habitat: Cameroon

Colouration: a) Male. The basic body colour is olive green, with deep red markings. From the operculum back these are horizontal, and take the form of red spots. From above the ventrals to the caudal, they are darker, almost brown, and take the form of nine or ten vertical bands. The belly is a dirty white, or pinkish, depending on the individual. The sides of the head and the operculum, are green, the operculum being particularly brightly coloured. The dorsal is green, boldly marked deep red. The front edge is yellow, and the top rays are filamented. The anal is green, the lower half bearing a wide deep red band, edged yellow. The ventrals are yellow, with a few red spots. The caudal has three vertical red bands on a green background, with a red border. The pectorals are colourless.

1. b) Female. Light brown, with darker edging to all the scales, forming a faint diamond pattern over the whole body. There is a distinctive triangular marking, reddish, at the base of the dorsal.

Maintenance: Not a difficult species to keep in good condition when adult, although the young have caused me a lot of trouble. Normal “killie water” i.e. pH 6.4-6.8, as soft as possible, a temperature in the low seventies, subdued light, and plenty of live food seem to suit them well. I estimate that the oldest pair I have are about eighteen months old, and still spawn regularly although they have never been prolific. I have never tried to feed them on dried food but they will accept all the usual live foods. The male is quite peaceful, and I have never found it necessary to separate the female.

Breeding: I classify killies in three ways where breeding is concerned, easy, difficult, and misbegotten, and this species is the only one to fall into the third category. I can manage to rear just enough young to keep the strain going, and that’s all. Spawning is quite normal, largish eggs deposited singly on sunken peat or near the bottom of mops. Ten a day is a good number, three or four being more common. Here the trouble starts. The slightest impurity in the water and the eggs decay after six to eight days. I keep the eggs in fresh rainwater, pH 6.9, hardness under 20 ppm. All being well, eggs kept at 72F. hatch in twelve to twenty days, but many eggs hatch prematurely, as shown by large yoke sacs on the fry. Such fry may not attempt to swim or eat for up to ten days, but the survival rate is just as high as with the fry which later and start swimming immediately. The fry are quite large, bigger for example than young Aphyosemion australe but seem very delicate. Belly sliders are common, and very many fry die in the egg. A few accept brine shrimp readily, and do well for about a week, but then most of them lose interest in life,sink to the bottom and soon die. Water changes and different foods seem to make no difference. Those which survive, about 5% of the original number of eggs, grow steadily rather than quickly and reach maturity in three to four months.

Summary: A most attractive, peaceful and desirable little fish, but its breeding is likely to pose a challenge to most aquarists, and not therefore liable to be easily obtained at present. It is possible that better results could be obtained by drying the eggs for four to six weeks, and in fact I intend to experiment in this direction if ever I manage to get a sufficiently large stock to make experiment practicable.

References:
Killi-Data A.exiguum
Killifish of West Africa A.exiguum