Copepods & Amphipods

Found tiny white bugs in your tank?

What are they?

These tiny microscopic-like white bugs swimming or crawling all over your tank. What you are most likely seeing are Copepods and/or Amphipods. These are shrimp-like crustaceans that dwell in the substrate as adults, but during their larval and juvenile stages are most often free swimming.

Basic facts about these tiny crustaceans

• There are both pelagic (free swimming), and benthic (bottom dwelling) bugs.
• Copepods occur in all types of aquatic ecosystems; freshwater, estuarine (brackish) and marine.
• Amphipods are mostly found in marine ecosystems, but there are some freshwater and terrestrial species.
• They are just a few of the tiny animal organisms that make up zooplankton, which contributes to the make up of plankton.
• These creatures eat phytoplankton (tiny plants and algae that also help make up plankton), small microzooplankton (the division of zooplankton that are smaller than 200 microns, or 1/127th of an inch in size), and detritus.
• Only a few of the thousands of species of copepods and amphipods known are carnivorous or parasitic, and these are rarely found in a saltwater aquarium system.
• For many saltwater fish and other marine species, copepods and amphipods are a primary food source, both in nature and in captivity.
• Because these tiny organisms are a natural part of the plankton food chain in the ocean realm, they are naturally going to occur in a saltwater aquarium environment. They are also micro-cultured as food for various species of adult marine animals, as well as used and tested as a food source in the research of culturing and rearing all kinds of tank-raised fry.
• Copepods and amphipods most often appear in closed aquarium systems after live sand and/or rock has been added.

So what fish and other marine animals eat copepods and amphipods?

•  Mandarinfishes: Synchiropus splendidus, ocellatus, picturatus, stellatus, and Dactylopus dactylopus species. Actually Dragonets, Mandarinfish are members of the Family Callionymidae.
• Sand Sifting Gobies
•  Sleeper Gobies (Valenciennea sp.) 
• Signal/Crab Eye Goby (Signigobius biocellatus)
• Midas Blenny (Ecsenius midas)
• Seahorses

Amphipods (Grammarids) are one of the main live food sources of adult Seahorses, as well as newly hatched fry. They will wrap their tails around something stable and then feast on them as they swim or float by.

• Most Firefishes are planktivores and feed mainly on prey suspended in the water column, but may occasionally pick these bugs or other food off the substrate.
• Most Angel, Butterfly, Hawk and Wrasse fish species spend their days picking small crustaceaous life forms from rocks, corals, and the sand. Since copepods and amphipods are shrimp-like crustaceans, these types of fish do not consider them to be a primary food source, but may opportunistically feed on them to some extent when they are present.
• Carnivorous Crustaceans
• Many species of Shrimps, True Crabs, Hermit Crabs, as well as other crustaceans that are carnivores. Carnivorous Invertebrates. Many SPS corals and other animals such as Gorgonians and other soft corals feed on plankton, as well as get nutrition from plankton byproducts.

So what do you do if your aquarium does not have a good bug population present to sustain these types of fish and you don't want to wait around until one develops, or their numbers are taking over the aquarium and you want to control or remove them?

How To Control or Remove Copepods and Amphipods

Even though considered a food source to some tank inhabitants, these bugs are considered no more than a nuisance to others. Sometimes when very large populations of these bugs are present in the free swimming larval and juvenile stages, you may see fish in the tank shaking or shuddering. This is because the bugs crawl around on the bodies of the fish, causing what you might explain as a tickling sensation that is annoying to them. This can become overwhelming and exhausting for the fish, because they find it difficult to get any rest as they constantly move or dart around to keep the bugs off of themselves.

If this happens and you are concerned about your fish, and you do not have any bug eating animals present in the aquarium to help reduce their numbers naturally, it may be necessary for you to take steps to control or thin them out. This can easily be accomplished by simply running a hang-on-tank type canister filter (read reviews compare prices) with a fine micron sleeve or pleat cartridge on the aquarium for a short period of time to filter the bugs out of the water.

Remember, these tiny bugs are a beneficial and natural part of a good balanced aquarium ecosystem, and an important food source required by some species to survive! They aren't really hurting anything, and unless they are causing a big problem for the fish or other tank inhabitants, you shouldn't have to do anything about them. Once they grow to maturity, they will retire into the rocks and substrate of the aquarium.

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