To keep your marine aquarium clean and healthy, it is important to add some useful creatures who will graze on algae and polish off left over fish food. These mobile invertebrates are referred to as a marine Clean Up Crew, and sometimes abbreviated to CUC. Here’s a guide to some of the most useful tank cleaners.

 

The Mithrax crab

Also known as the Emerald crab, this green crustacean will consume nuisance bubble algae, unlike most other animals. In the absence of this, they will graze on other algae and uneaten food. It is nocturnal, and prefers to hide during the daytime, only coming out at night to forage.

If there is not enough algae in the aquarium, it may eat corals and invertebrates and small fish, so supplement its diet with seaweed and chopped shrimp if necessary, and only add one crab per 22 gallons of tank volume.

 

Hermit crabs

This crab thrives on algae and detritus and will hoover up any uneaten food. There are numerous species available but stick to the smaller reef-friendly types, at a ratio of about 1 per 5.5 gallons of tank volume. Some species may attack snails and steal shells from other crabs, so ask your marine vendor for some expert advice.

 

Peppermint shrimp

These red banded shrimps are useful for eating nuisance Aiptasia anemones. They will also scavenge over live rock for composting organic material, and polish off uneaten food. They are reclusive in nature, but also known to breed when given the opportunity.

 

Snails

The Trochus and Astraea species are considered the most useful types of snail to add to your tank. These algae grazing snails are particularly effective at keeping the sides of the glass clean, although they will also consume from rocks and sand. About five snails should be adequate for an average sized tank.