Aquarium glossary
The terms you need to manage your aquarium. Each definition includes recommended values for marine, tropical freshwater, coldwater and brackish aquariums, as well as ponds.
24 terms in "Problems and pathologies"
Aiptasia
Infesting anemones that arrive with live rock. They reproduce rapidly and sting nearby corals. One of the most hated parasites in the reef.
Algae in aquarium
Algae are photosynthetic organisms that proliferate when light and nutrients are in excess. Some are beneficial (coralline algae), most are unwanted.
Allelopathy (chemical warfare between corals)
The release of toxic substances by corals and invertebrates to compete with their neighbors. An often underestimated factor in reef design.
Aluminium in the aquarium
Metal contaminant that should not be present in aquarium water. Even in trace amounts it can damage corals and invertebrates.
Blackout (darkening of the aquarium)
Emergency technique against algae: the aquarium is completely darkened for 3-5 days.
Chlorine and chloramines
Disinfectants present in tap water. Deadly for fish, invertebrates and filter bacteria. They must always be neutralized before use.
Columnar disease (Columnaris)
Bacterial infection that causes white cottony patches on the mouth, fins and body of fish. Often confused with a fungus but it is bacterial.
Cyanobacteria (cyano)
Cyanobacteria are photosynthetic organisms that form red-brown slimy mats in the aquarium. They are not algae but bacteria capable of photosynthesis.
Diatoms
Brown unicellular algae that appear in new aquariums. They form a brown film on glass, substrate and decorations. They disappear on their own as they mature.
Dinoflagellates (dino)
Dinoflagellates are single-celled organisms that can infest a marine aquarium with a mucilaginous brown coating. They often appear in aquariums with ultralow nutrients.
Dropsy (ascites)
Condition in which the fish swells with raised scales (pine cone appearance). Often a sign of kidney failure or serious bacterial infection.
Filamentous algae
Green algae that form tufts and filaments on rocks, plants and decorations. Sign of imbalance between light and nutrients.
Fin rot (fin rot)
Progressive deterioration of the fins caused by bacteria. The fins become frayed and shorten. Almost always linked to poor water quality.
Fish diseases
Fish get sick due to stress, wrong parameters, bacteria, parasites or viruses. Recognizing symptoms early makes the difference between an easy treatment and a fatality.
Green water (algal bloom)
Massive proliferation of suspended unicellular algae which makes the water green and opaque. Common in ponds and aquariums exposed to too much light.
Ich (white spot disease)
The most common disease of aquarium fish. Caused by a parasitic protozoan that manifests itself as white dots on the body and fins.
Lead in aquarium
Highly toxic heavy metal. It should never be present. Deadly for invertebrates and fish even at very low concentrations.
Nickel in the aquarium
Contaminating heavy metal. Even in small quantities it can damage corals. Its presence almost always indicates a problem to be solved.
Pest snails
Snails that arrive as stowaways on plants and reproduce explosively. They are not harmful but can become unsightly.
Planarians
Flatworms that infest freshwater and marine aquariums. In freshwater aquariums they threaten shrimp colonies. In marine aquariums they attack corals.
RTN and STN (coral necrosis)
Rapid (RTN) or slow (STN) tissue loss in corals. Causes include stress, unstable parameters, bacterial infections and contamination.
Tin (Sn) in aquariums
Contaminating heavy metal. It should not be present in the aquarium water. Toxic for corals and invertebrates.
Valonia (bubble algae)
Spherical green algae growing on rocks in marine aquariums. Unsightly and difficult to remove. Emerald crab is the best organic remedy.
Velvet (Oodinium/Velvet Disease)
Parasitic disease that coats fish in a golden or gray powder. More dangerous than stroke because it is often diagnosed too late.