Bubble algae typically forms in red or green bubbles on a hard surface such as a rock. It is a nuisance for saltwater aquariums because it grows rapidly and crowds out desirable plant specimens. There are some tank dwellers that can eat enough bubble algae to control it in a tank environment.
Mithrax crabs, in particular the Red Mithrax, are close relatives to Green Emerald crabs. The Mithrax crab will eat leftover foods as well as bubble algae. They are an offshore crab, so they tend to be suited for reef tank environments. Mithrax crabs can be mixed with Emerald crabs in a tank environment. A Mithrax will grow to a maximum size of about 1 1/2 inches in width.
Sally Lightfoot Crabs
Sally Lightfoot crabs are scavengers that will eat bubble and hair algae. They are a docile species with a green-brown exterior and yellow markings around the leg joints. The Sally Lightfoot crab has two antennae at the front of its body, and those antennae are always moving. Sally Lightfoot crabs get along well with other inhabitants in a reef tank but will compete aggressively for food. They may eat sick or injured fish.
Green and Ruby Emerald Crabs
Green Emerald crabs and Ruby Emerald crabs are small and will not harm other fish in your aquarium. They will eat nuisance algae and meaty foods the fish miss. Green Emeralds have a flat, shiny green body and hairy legs. It is nocturnal, so the host aquarium will need plenty of rocks and hiding places for it to go during the day. The Ruby has a red, bumpy body and pink hairy legs. Although these crabs eat bubble algae, this is not a sufficient diet alone. They also need dried seaweed, chopped meats such as shrimp, and pellet food.
The Desjardini Sailfin Tang and the Yellow Hawaiian Tang are among the few fish that have been known to eat bubble algae, but this is not guaranteed. They have also ignored it. The highly active Desjardini Tang requires a large tank of at least 4 feet in length. The Yellow Hawaiian Tang is an oval-shaped, bright yellow fish common in many home saltwater aquariums. Tangs are aggressively territorial toward their own species, so it’s best to have only one per tank.