The tank is a constant balancing act. Food added is converted to waste, either through digestion or decomposition. If that waste builds up too much the inhabitants of the tank will start suffering. I can’t very well just stop feeding the tank though, so what to do about the waste?
There is a whole class of critters in the tank that is collectively known as “The Cleanup Crew”. These guys were the heroes with regards to the recent loss of my Firefish since they were able to find and devour its body before it could decay too much. More generally, they are detrivores, largely eating food debris from me overfeeding the fish. While they all fall under the Cleanup Crew category the group is composed of quite a few species of animal.
Snails
Astrea – These spiky snails are good all-rounders, eating film algaes, hair algae, cyanobacteria and diatomes. They’re good at everything a snail should do except flip over when they fall on their back. Which they do. Frequently. Unfortunately, other members of the cleanup crew aren’t picky about their food being alive or not and will take full advantage of this.
Trochus – Astreas except they can flip themselves over and they move faster.
Bumblebee – Small snails which seem to have particularly good senses of smell. They always seem to be the first at the scene of a death. They try to hide in the rocks as best they can during the day.
Nassarius – These guys also have good senses of smell. They all end up at the same piece of food or dead snail quite quickly. When not on the hunt they bury themselves in the sand with only their snorkel exposed.
Crustaceans
Emerald Crab – Hairy Legs, our sole Emerald Crab. He used to have a tankmate but they had a falling out. The other crab ended up with a single leg and claw before finally dying. This guy eats everything and even seems to break small pieces of rock off for fun. His name comes from his bristly legs. From my reading it sounds like some crabs pull the hairs off their legs and some don’t, and there’s apparently no rhyme or reason to it.
Scarlet Legged Hermit Crab – A mostly peaceful hermit crab. These guys try to get into snails if they find one on its back but I’ve never seen them succeed. Snails have a kind of trapdoor on the back of their foot which they use to block the entrance to their shell.
Blue Legged Hermit Crab – A much more aggressive hermit crab which does succeed at getting into snails. They also try to pull the scarlet legged crabs out of their shells.
Copepods – Tiny crustaceans, varying from the size of a gnat to the size of a large gnat. They are frequently cleaning the bottom of the glass and in patches of hair algae. They breed constantly and many fish enjoy eating them, providing a constant nutrient source as long as they don’t all get eaten. There are hundreds if not thousands of them in there.
Others
Lettuce Nudibranch – This guy is fascinating. They consume algae but don’t digest it in the traditional sense, instead, they steal the chlorophyll from it and photosynthesize. It also looks extremely doofy.
Bristleworms – While they look gross they are important detrivores. They seem to eat everything and also provide a food supply for the coral-banded shrimp.