I have a theory regarding breeding success of these opae ulas. They don't like one constant temperature all day. Mine are constantly producing eggs. I started out with 10, and now I think I have more than 60 in less than 2 years. (There are at least 3 berried shrimps right now--4 yesterday, but I notice over 10 new babies floating today). I don't feed them or change the brackish water. I only top up with fresh water. I haven't changed any water for fear of scooping out all the little ones by accident. I don't use a heater. I suspect that they like some temperature variation, like in nature--day and night fluctuations. I just keep mine by a south/west window and leave them there at room temp (20c). It would get slightly cooler by the window where I live each night.
I do worry that the temperature would get too cold for them in the winter here if it dips below freezing for more than a week at a time. Though, it hasn't been a problem yet. Is there such a thing as a heater that has varied time temperature settings? for a teeny tiny tank (gallon and a half)?
loraxchatter wrote: Is there such a thing as a heater that has varied time temperature settings? for a teeny tiny tank (gallon and a half)?
No, but you can buy a timer for your heater so it turns on at certain times of the day (e.g. only during the day, off at night, or vice versa). With some experimentation you can find the settings for your needs.
i´m still not an opae´ula expert, but I think, that temperature variations are good, because in nature, especially in shallow water, the temperature also varies. my opae´ulas live at room temperature and I think, they are doing fine. I admit, that in summer I tried to cool the water with ice, because I think, there´s a limit in high temperature rather than in low temperatures...