By Charles Nunziata
There are several explanations of why most hobbyists are not aware of South American annuals and many have not seen one alive. First is their absence from consumer outlets and the relative lack of coverage in hobby communications. In addition, there is a widespread perception that all killifish have a short lifespan. Although this is not true of non-annual killifish, it is true of the annuals, and that fact alone is often a deal-breaker for some hobbyists. Lastly, killifish are considered to be difficult to breed and maintain, but this is not accurate.
General maintenance is not overly demanding, requiring only regular water changes and the provision of high-quality foods. Most annual killifishes can withstand large temperature variations, but as in most other fish, thermal shocks should be avoided. Mid-range hardness and temperatures in the 70s are ideal. Temperatures lower than 70 slow activity, and above 80 will accelerate aging. They do not thrive in poor water conditions and will not develop properly if undernourished, but any experienced aquarist to whom good aquarium practices are second nature will have no difficulty maintaining these species.
South American annuals tend to occupy all areas of a tank, are moderately active, and with some exceptions, are not aggressive to other killie or non-killie species. Rather, their color and finnage often invite aggression from other species. Non-aggressive species that are not overly active can safely be kept with most annual species. However, it is the practice of most killifish hobbyists to maintain South American annuals in species-only tanks, and better success can be expected if that method can be adopted. Tanks as small as 2½ gallons are sufficient for a few of the smaller species, and 5- or 10-gallon tanks are ample for all but the largest. Feeding is likewise straightforward. Live and frozen foods of all kinds and, with training, freeze-dried bloodworms and similar-quality foods will be readily taken.
The major difference between South American annual killifish and other hobby species is the time it takes for the embryos to develop. The eggs of non-annual fishes incubate and hatch within days or weeks, while annual eggs take months to develop and may well hatch after their parents are gone. The months-long uncertainty associated with not knowing whether a spawning has been successful is not compatible with everyone’s personality and is often the root of the idea that breeding these fishes is difficult. Killie-keepers have to be a patient lot.
For more information on breeding annual killies and what species are available, see my article in the June 2013 issue.