A single paramoecium - Photograph Adrian BurgeMany young fish are so small when they first hatch that they can not eat traditional 'first foods' such as newly hatched artemia, microworms and vinegar eels. Amongst the nothos, this is particularly the case for N. janpapi, N. luekei and N. geminus - the Aphyobranchius subgenus. Other Nothobranchius, particularly from young parents, can also have similar problems (N. rachovii and N. patrizii spring to mind).

Infusoria is the collective name for microscopic organisms that dwell in bodies of water, feeding on detrietus and smaller single celled organisms, and include rotifers, and paramoecium. These micro-organisms live amongst plants, gravel, and in the filter, in fact anywhere they can. Squeezing out a sponge filter will yield a large number of these infusorians. For most (non-surface dwelling) fry it is ok to simply let them grow for a few days in a well matured tank with a sponge filter, or with a large clump of javamoss. A few days on and the fry will be eating newly hatched artemia nauplii - so why bother to raise paramoecium?

The smaller nothos (Aphyobranchius species) are surface dwellers, the newly hatched fry spending their first days living at the very surface of their tank - often in the meniscus around the edge. Because of this tendancy to remain near the water surface, the infusoria associated with plant matter ...