Hi everyone,
I started breeding Fundulopanchax nigerianus gardneri Makurdi several months ago. I am having great success in obtaining eggs and fry seem to be growing reasonably well.
However none of the fry so far seem to be males. The oldest batch are already 2.5 months old. They are under an inch in size but have almost no color. I am reading about how this species is notorious for having extremely skewed sex ratios.
Surprisingly, there is very little information on this in any of the literature for beginners. I choose this species since it was recommended for beginners. Anyone have any advice? Is it possible some are males but havent colored up yet?
Salvatore
In some killifish species specifically louessense, I’ve had great success lower the water temperature 2-3 dgF, for males, I’ve had large male populations >85% @ 72-73dgF, when lowering the water temp to distinctly below 71 68-69 dgF, I reared a much larger >50% concentration of males. Some believe as I that killifish have what know as crocodile syndrome, where eggs raised at temperatures produce the same sex, so they have less chance to interbreed with siblings.
To do this I placed my tanks nearer to my basement floor to lower the temperature. Just something to try… Let us know how things work for you,
Jim Langan AKA, Webmaster
Salvatore
One thing I forgot to mention is incubate my killi eggs in water tight containers inside the tank with the adults so the eggs incubate at the same temperature for development. So the eggs are at a very stable temp, the are different publications on egg development temp and its likely that sex is determined during development not at fertilization. I’ll try to post some photos as to how I do this…
Keeping your temperatures 2-3 dgF apart will make a difference one way or the other
Good Luck, Jim Langan, AKA Webmaster
Still getting what seems to be only females (already 8 fish). They are beyond 3 months so I am assuming this is what they are.
I am going to try the ice cube tray method. Did you provide different water conditions in each partition?
No, raised all the fish in the same water.
One other thing. You can’t really determine much from just 8 fish. Pick eggs every day for a week till you’ve got about 50, watch them for a few days and get rid of the fungused ones, then raise the remaining fry and then see. I’d do that before messing around with ice cube trays, it really is a pain.
