General information
The Least Killifish, Heterandria formosa is a small, livebearing fish that originates from North America. It is from the same family as Guppies and Mollys. This is the smallest fish found in North America, and one of the smallest fish in the world.
Tank setup
My experience with this fish started because I found the colony behavior of the fish very interesting. At the local fish store, The Fish Place, they had a colony that contained many different aged specimens all living in the same tank. The larger fish didn’t seem to bother the smaller, and the fish sort of hovered in groups, and didn’t really school. A second reason for me to want these fish was to see if I could spawn the fish and turn them in for points at my local fish club. I purchased a pair of fish from the LFS, and took them home.
After acclimation, I placed the pair into a 55G community tank that housed Discus (Symphysodon spp.), Cory Cats (Corydoras aeneus), and Bristle-nose Plecos. None of the other fish in the tank seemed to notice the new inhabitants. After about a month, I couldn’t spot the male, and Assumed he must have died. In a tank that large, it was hard to find a body. On my next trip to the LFS, I picked up another pair. The colony has really taken off over the past 3 weeks, because I moved out the other inhabitants of this tank. The tank is divided, and Heterandria formosa has half the tank to themselves (except for the assassin snails).
This fish is so small, that keeping the tank with a bit of mulm on the bottom is a good thing. My tanks always have some live plants and driftwood to give the fry some refuge and grazing sites. Currently, there is a colony of about twenty fish including the parents, that I plan on moving to their own 10G tank as soon as I get it cycled. The smaller fry in the tank will be of sufficient size for me to turn in at the local club meeting in a month and a half, and the remainder will probably be kept until the next big fish auction.
Parameters and feeding
The average tank parameter are as follows:
- Ph – 7.0
- Temp – 78.5
- NH3/NH4 – 0
- TDS – 103
- GH/KH – 17.9 – 35.8 ppm
Water changes are done daily at the moment, as there are Discus fry on the other half of the divided 55G tank. The feeding is two or three times a day with some crushed flake, microworms, or baby brine shrimp.
Overall, the Least Killiefish is an ideal nano tank inhabitant. The fish are really hard to enjoy in a large tank, and seem to hide most the day when housed with larger tank mates. Their demands seem to be pretty low, and breeding the fish is as simple as supplying a same tank and small food to nourish the parents.
References
Fishbase.org – Heterandria formosa Girard, 1859, Least killifish
http://www.fishbase.org/summary/Heterandria-formosa.html
Wikipedia “Heterandria formosa”
http://en.wikipedia.org/wiki/Heterandria_formosa
Source: http://fish.joshvito.com/breeding-heterandria-formosa/
© Photos by the author