My most prolific breeding pair of Julidochromis dickfeldi recently spawned again. The best I could tell, it had been at least three months since their last spawn. Why?
There are several reasons why your fish might pause their spawning. One of the most common is that, by retaining multiple broods in one tank, there is greater social pressure – more threats and greater competition for resources. What this means in simpler terms is that the more offspring that are left in the tank rather than removed, the greater pressure placed on the parents when reproducing. Obviously, the size of the tank factors in. My most prolific pair of dickfeldi reside in a 20g long tank. They’ll happily do the deed regularly until about the third brood. That size tank gets crowded quickly. If they were in a 75g tank alone, they may press on through eight or nine broods.
Thus, in a smaller tank, a breeding pair is likely to slow their reproductive cycle if you don’t remove the offspring. As a rule, dickfeldi, like most julies, will spawn every few weeks. Brood size (number of eggs produced per brood) is a product of many variables – what you feed, the environment the fish are in, the biology of the fish themselves (see this article for more easily digestible information), and probably several others. Because I don’t actually count eggs when they’re laid, I can’t say what percentage actually become viable. What I can say, is that by the time I see the fry, there are normally around 30-40.
Julies aren’t large cichlids. With an adult dickfeldi male topping out about 4″, they are reasonably representative of species size in the genus. Their brood size is typically small also. Many of the cichlids of Central American, for example, can produce hundreds of offspring at a time. In fact, check out the offspring of the pair of Herichthys cyanoguttatus (Texas cichlid) in the photo below.
One reason my productive pair of dickfeldi spawned recently is because I just removed about 60 juveniles from that tank. All of those juveniles comprised at least five broods. I have no idea how many fry are in the tank now.
What I do know is that, until doing my regular water change last night, I did not know the pair had spawned again. In fact, it wasn’t until I had vacuumed near their ceramic cave that I saw one fry dart around a rock. By that time, I had already vacuumed two of them up. Don’t fret though. I have a water change/vacuum routine that includes a safety net in the event I ever accidentally vacuum up fry. Both fry are back in the 20g tank with their tankmates.