Copepods

Copepods are a tiny crustacean that are found in both saltwater and freshwater. They make up the zooplankton chain of food which is right above phytoplankton.

As such, they are absolutely essential to the continued existence of aquatic fishes, crustaceans and other creatures such as some types of planktonic consuming whales. Within the zooplankton hierarchy, they are usually the top do

They are a very important daily food item for some marine aquarium fish including the Mandarin Fish and the Scooter Blenny. Copepods are thought to make up the largest biomass of any known species on earth. To date, there are over 10000 known species of this tiny crustacean.

Some of them are herbivores, carnivores and even parasites that attach themselves to fish and crustaceans.

They make up the first foods for a wide variety of sea organisms that include fish larvae, crab larvae and shrimp larvae.

Some plankton eating mammals also rely heavily on copepods for sustenance. Whale sharks, blue whales and some birds consume copepods on a daily basis.

There are two primary types of copepods, benthic and calanoid. Calanoid copepods exist in the water column where they feed and breed. Calanoid variants are the type most commonly consumed by larvae.

Benthic copepods exist on a substrate of some sort. Usually the ocean floor, rock, corals and anything else that they can crawl upon.

In the marine aquarium hobby, copepods are imported into our tanks via algae, live rock as well as water. The most successful of them are benthic as almost everyone in the hobby has witnessed copepods crawling on their glass, substrate and live rock.

They are a beneficial addition to any tank as they are usually harmless herbivores that are also consumed by a wide variety of organisms in the captive marine aquarium. No care is required for the continued existence of this crustacean in captivity as they feed and breed on their own with ease.

Copepods have a huge impact on tank rearing efforts of certain species of fish and invertebrates. Certain types of fish larvae simply cannot make it through to adulthood without the presence of copepods as a first food.

Dwarf angelfish are one of those organisms. In the past, a great variety of foods were used with angelfish larvae but it was found that there is no substitute for zooplankton. In fact, the copepod is responsible for the first major breakthrough the marine industry has had with regards to dwarf angelfish.

It was found that an undisclosed type of copepod nauplii is essential in the diet of all centropyge angelfish. Certain ornamental marine fish such as the Mandarin fish and seahorses (at least their larvae) rely very heavily on existing copepod populations.