Many hobbyists may decide to stray from the usual route of fish and go with a type of invertebrate. When many people think of invertebrates and aquariums, they think usually just make a mental connection to snails. But there are many invertebrate species for your freshwater aquarium including freshwater lobsters, freshwater shrimp, ornamental snails, and freshwater clams.
Most freshwater invertebrates are also very functional; they have a tendency to feed on detritus and algae on the sides of your aquarium or scavenging the bottom for uneaten food and organic debris. They are considered to be the equivalent of a janitorial staff; helping keep your aquarium clean, clear, and healthy.
Most invertebrates are omnivores, so should be equipped with a balanced diet. They require clean, clear water, adequate oxygen and a steady current. Temperaments of invertebrates range from peaceful to semi-aggressive, but should not pose a problem when housed properly with appropriate tank mates. For the most harmonious results, avoid putting organisms in the tank that may end up a side dish.
Keep in mind that even peaceful invertebrates can become aggressive in isolated situations or under certain circumstances. Factors contributing to aggressive behavior include stress, an unpleasant environment, or insufficient diet. However, if you care for your invertebrates and their aquariums properly, the chance for potential problems decreases.
Invertebrates are not only sensitive to water quality, they are also often vulnerable to medications you might give your fish. They are exceedingly sensitive to copper or copper derivatives that you might put into your aquarium to fight fish parasites or disease.