As time goes by and the population matures, you might even be lucky enough to see some little baby fish frolicking with their older siblings.
The key is keeping the whole menagerie spotless. You’ve got to keep the water filtered and the gravel clean. Fail to do that and you could wind up with your pets swimming in their own poo - or worse, you could wind up like the guy in the video below. Unbeknownst to him, a bristle worm was living – and growing – in his set-up. Two years later, when he finally went to clean it, Poseidon unleashed his wrath and this 1.2 meter monster came flowing forth. It really looks horrible, like an aquatic centipede or millipede.
Apparently, bristle worms aren’t all that bad. You wouldn’t want them snuggling with you in your bed at night, but they aren’t poisonous or otherwise lethal. They do look like the stuff of your night terrors; you can imagine it slinking around beneath the surface as you struggle to see what’s brushing up against your slowly paddling legs. As we said, you need to keep your little undersea kingdom clean. If you don’t, you might just end up with dead pets, and one massive water worm to worry about.