Keeping Endlers with Least Killifsh.

[ustabefast]

I've had a shoal of Least Killifish, aka Heterandria Formasa for a couple years.
A couple months ago I saw female Endlers at the lfs and on a lark, I bought 3 of them along with a single male.
I thought it would be interesting to see how they interacted with the similar sized Least Killis.

Well, it's a couple of months later and I now have something like 150 Endlers.
I have maybe 7 or 8 least Killis left.
The Endlers certainly outbreed the Killies.
One interesting observation, my pregnant females gave birth to only males for several weeks it seems.
I now have many more adult male Endlers than females, but dozens of fry appear to be female..

Also, my Endlers and Killis never even attempted to interbreed. They ignore each other.

 

[Tifftastic]

I'm not surprised they never tried to spawn with each other as the mating habits are pretty different and the species are far removed from each other phylogenetically.

As for the sex ratios you are seeing, I wouldn't be surprised if temperature played a part in sex determination as it is not uncommon in some lab strains of guppies and other poecilieds to exhibit changes in offspring sex ratios based on temperature.

 

[ustabefast]

The water temp in this tank is low 70's.

 

[fishorama]

I don't know if it holds true for endlers but when we had kribensis water hardness seemed to have an influence on fry gender.. We had batches of mostly males (ok, larger & tougher even as fry) but also some spawns of mostly females. Temp the same.

Some places I've lived have "seasonal" water differences in GH & KH depending on snow melt vs aged groundwater. & of course, in CA, we can have big temp swings too. I dunno...I don't test often.

 

[ustabefast]

Well, whatever the reason, I have lots of pretty male endlers now, but I feel for those 3 original females who are huge and bloated with fry and each routinely chased around all day by a lots of males.
I keep the fish in pretty soft water, tds 150, neutral ph., and I believe Endlers originate in warm, harder tropical waters.
One thing for sure, Least Killifish are no match for Endlers in this tank.

 

[OrionGirl]

Endlers = guppies. Really. Their status as a discrete species is tenuous at best.

I am in the process of removing endlers completely from my tanks because they have shown they can takeover and fill a tank from a single pregnant female. Females live longer than males and can store sperm for several months. I'd remove some of the males, or the larger females will start killing them off. And, I'd rescue the least killies you have left and rehome them, unless you no longer want them at all. I had beckfords pencils in the endlers--before the endlers, they'd add 2-3 to the school each month. After adding the endlers, no more fry survived. Removed the endlers, and within a month, I had 6+ pencil fry.

 

[ustabefast]

Yeah, I'm going to start rehoming the Endlers, maybe keep a few of the prettier males in my other tanks.
I'll just give them away on craigslist. The local fish store has 1000s of them, both adults and fry, so I'm guessing they will not be interested.

 

[fishorama]

Yeah, sounds like a plan. There a few endler people in my plant club that can't give them away anymore, good luck!

 

[OrionGirl]

Make sure to note they should NOT be placed in any natural water way. Endlers are not good for mosquito control, and should never be released. If you give them away free, lots of people might get that idea.

Check for local aquarium societies, as well. Monthly meeting auctions might not bring in much, but they'll at least sell to people with tanks.

 

[emeraldking]

In a way Tifftastic is right. Temperature can influence the sex ratio. But a larger male ratio with guppies and endlers do occur frequently with higer temps. With species like h.formosa it's the other way round. But you were saying that the the temps were low 70's. So, the temperature ain't the cause of the majority of males in this case. But hardness can influence this also a bit.

That endlers won't interbreed with h.formosa is obvious. H.formosa are superfetative and endlers aren't. It's a total different way of reproduction. And another reason is that the genitals of both species won't allow it. The gonopodia of both species are different shaped. Gonopodia of each kind of livebearer differ and such shaped gonopodia only fits in the female genital of their own kind or close related strains. So, there are two reason why an interbreeding between an endler and h.formosa won't happen.