The variety of organisms living in your aquarium that you don't see, probably outnumber the carefully selected pets that you do. Regardless of your efforts, tank bugs will take up residence in your meticulously kept underwater world. Some of these uninvited tank mates are rare and scarce; others are commonplace.
Freshwater Tank Bugs
Far from a nuisance, some tank bugs benefit your mini-reservoir, and are a sign of a healthy aquarium. A common class of freshwater tank bugs are arthropods, which include ostracods, copepods and mites. These underwater invertebrates are found in pond water and transfer to home aquariums through store-bought fish and plant life. Arthropods provide foraging food for fry and small fish, and devour undesirable detritus. Nematodes are thin hairless worms, forming an "S" shape when swimming. Daphnia, or water fleas, are harmless edible tank bugs, recognized by their erratic swimming motion. Hydra are semistationary organisms who attach to aquarium glass, plants and filtration equipment. With stinging tentacles, they pose a threat to fry, shrimp and smaller fish.
Eradication and Control
Many aquarists believe complete eradication of tank bugs is impossible. Keeping these potentially imposing aquaria at manageable levels is common practice, and accomplished through routine aquarium maintenance and proper filtration. For additional tank bug extermination and control, techniques vary. A strong flowing current, coupled with good filtration, are effective ways to minimize tank bugs. Worms, snails, limpets and various other tank bugs can be eradicated with commercially available traps. A high percentage water change also will help to control tank bug numbers.
Marine Aquarium Pests and Signs
Common tank bugs in saltwater aquariums include flatworms, amphipods, copepods, little red bugs, snails, sea spiders and coral-eating nudibranch. Because of its potential size, an especially disturbing polyphyletic intruder is the bristle worm. Untreated corals are often the mode of transportation for flatworms and uninvited stowaways. Novice marine aquarists should learn to spot unwanted tank bugs and after dark, nocturnal invaders can be located with a flashlight search. Signs of a saltwater tank bug infestation include loss of coral coloration, yellow or brown-red worms on glass and equipment, polyps refusing extension and receding montipora and acropora.
Saltwater Tank Bug Control and Treatments
To minimize the potential for introducing unwanted tank bugs to your marine aquarium, always treat new coral with coral conditioner. Live rock fragments, or frags, are often the source of marauding hitchhikers, and these reef-building segments should be processed properly. Methods of treatment for marine aquarium tank bugs include introducing natural predators, and veterinary recommended chemicals and medications. The dragonface pipefish (Corythoichthys haematopterus) is an example of a tank bug predator. These tubular fish anchor themselves on reef outcrops and feed on unwanted miniature crustaceans, bugs, snails and worms.