Least Killifish

  1. Piaelliott Well Known Member Member

    I became interested in Least killifish, Heterandria Formosa.

    Who keeps them and what is your experience? I can't find anything on this forum.
  2. BeanFish Well Known Member Member

  3. BettaPonic Well Known Member Member

    They are a great fish. I keep mine in a ten gallon, but a colony can be kept on a tank as small as five gallons. They are not fry eaters. They are better in a species tank. They are very tolerant of temperature and hardness. Seriously Fish has a great article. They will breed, but in my experience not as fast as Guppies. I do see aggression sometimes. I have never seen damage though. I would recommend not keeping them with shrimp. I have heard some people say they gang up and kill shrimp.
  4. Piaelliott Well Known Member Member

    Oops, I never got an alert :(

    Where did you get yours from? Currently my fish guy is trying to get some for me.

    I was thinking about keeping them in a 40 gal outside and then move them into a 10 gal inside. How many do you have? Picture?
    I read a lot online, seriously fish too, just wanted to hear personal experience. Thanks!
  5. BettaPonic Well Known Member Member

  6. emeraldking Member Member

    True! They're not fry eaters at all.
    They can be kept at lower temps. They even reproduce well at lower temps.
    That they don't seem to be so profilic as guppies has to do with the fact that these are superfetative livebearers. So, not comparable at all with guppies. Unborn fry are developing in several stages and each batch will be delivered in a period of 10-14 days (1-3 fry each day or even a day after). Different from guppies which will drop fry mostly within one day. Besides that, there's another difference in breeding with h.formosas. Female h.formosas won't store sperm packages unlike guppies, mollies. platies and swordtails do. So, in order to establish a new pregnancy, a new mating should take place.
    Where in general guppies, swordtails, platies and mollies will result in a higher ratio male offspring when kept at higher temps (and at lower temps more female offspring), h.formosa and neoheterandria elegans it's the other way round. H.formosa is also less shy than n.elegans. And n.elegans are more comfortable at a bit higher temps in comparison to h.formosa. Also n.elegans is a superfetative livebearer.
    H.formosa can be kept with other friendly smaller fish. Overhere h.formosa and n.elegans are kept together (won't crosbreed). I also keep h.formosa outdoors during spring till mid fall.
    fish march 8th 2016 065.JPG

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  7. Piaelliott Well Known Member Member

    Thanks for the detailed info. I already read about superfetation, interesting!
    Is it difficult to catch them in the fall? I assume fry is super tiny with the adults being so small.
  8. BeanFish Well Known Member Member

    @emeraldking, do you know how low Least killifish could go?
  9. emeraldking Member Member

    It takes time to get them out of the outdoor tanks. But I don't mind. But an adult female can grow up till 3,5cm max at full potential (sorry guys, we use the metric system). Males till 1 till almost 2cm max. But most males will just reach 1-1,5cm. And females in general an average of 2-3cm. But despite of the fact that these are tiny fish and the fry when born are just like small needles, these fry do grow up pretty fast.
    There are more livebearers which are superfetative. Even with mammals superfetation does occur. It does happen with humans as well. But that's just a low potential percentage with humans. But if that happens with people than two pregnancies at the same time will be the max (so, no twins but actual two embryos in two different stages). Specific sharks have superfetation as well.
    Last year, I wrote an article about the micropoecilia picta which breeding proces looked a bit similar to superfetative livebearers (which is a kind of weird for m.picta isn't a superfetative livebearer) in one of our quarterly magazines of Poecilia Netherlands. Micropoecilia picta is my all time favorite livebearer btw...
  10. emeraldking Member Member

    When kept outdoors for a longer period these fish do withstand temps at approximately 12 - 18°C. At least, overhere they are used to it. And again, these h.formosas still reproduce when kept at such temps. But in general, I'd prefer to keep them at an average of 18-22°C which works perfectly for them. But they do withstand higher rates as well.
  11. BettaPonic Well Known Member Member

    I don't want to sound rude, but do you have a source for them not storing sperm? I am open to it being true, but it is a big claim to me, sorry.