I’ve had experience with spawning my freshwater angelfish recently but have always removed the fry shortly after they became free-swimming. I was wondering how long the fry could stay with the adults if I leave them together.
The length of time you can leave free-swimming angelfish (Pterophyllum) fry with their parents depends on a number of things. However, because you are removing them after they have become free-swimming indicates that the parents are not given to eating their own offspring, as is somewhat common in freshwater angelfish – at least the domesticated varieties.
First, freshwater angelfish tend to produce a lot of fry each time they spawn, so when the fry become mobile, they take up a lot of space in the aquarium as they spread out looking for food. Unfortunately, if there are other tropical fish in the aquarium, any of the fry that wander away from the watchful gaze of their parents will likely be eaten. Many species of aquarium fish find fry to be an almost irresistible addition to the menu. To limit the losses of the fry, remove any other tropical fish housed in the aquarium.
Another predator to your freshwater angelfish fry could be your filtration system. Power filters are notorious for sucking up fry that venture too close to the intake tube. However, there’s an easy solution to that problem. You can “muzzle” your filter by simply wrapping the intake tube (and factory-supplied screen) with a piece of foam – in fact, an old filter insert would work very well for that. Keep the foam in place until the fry are no longer small enough to get through the factory-supplied screen on the end of the intake tube.
If there’s no predatory threat to your freshwater angelfish fry, and they have regular access to appropriate food, you should be able to leave the fry with the pair for at least three weeks. The longer you leave the fry with the pair, the more it will delay the onset of another reproductive cycle. Eventually the parents will tire of their fry, but by then you will have had to thin out the population unless you’ve spawned them in a very large aquarium. Be careful. It is easy to inadvertently overstock an aquarium by leaving in the offspring of a successful spawning. Once the fry look like little freshwater angelfish, it is probably time to move them and give the adult pair a break. Good luck!