Cichlids, which feature prominently in the aquarium hobby, are brutal on plants. Some cichlids consider common aquarium plants a nutritious treat or disrupt their roots with digging, but moss is one of the few plants most cichlids won't enthusiastically decimate. Cichlids may graze on moss, but they will rarely completely devour it they way they do other aquarium plants.
Cichlids and Plants
With some exceptions, most cichlids do not get along well with live aquarium plants. Most medium-size to large cichlids will eat aquarium plants. In fact, feeding cichlids cheap aquarium plants like anacharis or duckweed can help keep a cichlid diet balanced. And many cichlids dig, either to create spawning nests or hiding places, disrupting vegetation. However, mosses usually grow quickly and do not attract the attention of vegetarian cichlids. Additionally, most mosses do not root in the substrate, making them ideal for sharing an aquarium with cichlids.
Technically, the fuzzy green balls sold in pet shops are colonies of algae, not moss. But they sell under the name "moss balls." Many cichlids like to graze on algae and will roll these green spheres around the aquarium while nibbling at them. Even under moderate lighting with no supplemental carbon dioxide, moss balls will grow fast enough to keep up with cichlids' nibbling.
Java moss is a near-perfect plant to share an aquarium with cichlids. This moss can grow under almost any water conditions, from the soft, acidic water associated with Amazon dwarf cichlids to the hard, alkaline water preferred by the famous cichlids of the African Rift Valley. Even better, it adapts equally well to low light or intense lighting. Java moss doesn't seem to appeal to most vegetarian fish, but cichlids may nibble on it a bit. Additionally, you can grow Java moss by tying it to rocks or driftwood. The moss will quickly attach to the surface and grow along it. This protects Java moss from cichlids' digging, since it doesn't need to root in substrate.
While moss balls and Java moss are common in pet shops, other mosses, like Christmas moss, show up. However, many mosses in pet shops prefer subtropical or temperate temperatures, making them unsuitable for the cichlid aquarium. Also, terrestrial mosses usually can't live in aquariums, so do not collect moss for your aquarium from the wild. Always research any type of moss you want to keep in your aquarium before you add it. An unhealthy moss can die and foul the aquarium water.