Copepod

Copepods are small aquatic crustaceans that make up one of the most diverse metazoan groupings found in aquatic environments. Copepods live in a wide range of salinities, from fresh to hypersaline, and can be found almost anywhere there's water: from subterranean caves to pools collected in bromeliad leaves or damp leaf litter on the ground, from streams, rivers, and lakes to the open ocean and the sediment layers underneath. Their habitats range from the deepest ocean trenches to the highest alpine lakes, as well as the frigid polar ice-water interface and heated active hydrothermal vents. On practically every major metazoan phylum, copepods can be free-living, symbiotic, or internal or external parasites.

Adults usually have a body length of 1-2 mm, however, free-living species' adults can be as tiny as 0.2 mm or as long as 17 mm. Body lengths of parasitic forms on large vertebrate hosts can surpass 20 cm.

The planktonic copepod is an ecologically important link in the aquatic food chain, feeding on phytoplankton's minute algal cells and being consumed by juvenile fish and other planktivores, including certain whales. By devouring mosquito larvae in freshwater, copepods have the potential to operate as a biological control strategy for malaria. They do, however, function as intermediate hosts for a variety of animal parasites and even human parasites, such as the fish tapeworm and guinea worm.

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Despite the fact that many copepod researchers are also interested in these external parasites of fish and amphibians, Branchiura (also known as fish lice) is discussed alongside the Copepoda. The majority of species dwell in freshwater, although roughly a quarter of them are marine. Over 200 families, 2,600 genera, and over 21,000 species have been identified in the Copepoda and Branchiura (both valid and invalid, including senior and junior synonyms).

Ectoparasitic Copepods

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Ectoparasitic copepods have been found in a variety of aquatic creatures, including crustaceans and shellfish. With the exception of the salmon louse, Lepeophtheirus salmonis, we know very little about parasitic parasites in commercial species.

Ectoparasitic copepods especially belong to the Caligidae family. It is the most common crustacean parasite on fish. The Caligidae is the biggest parasitic Copepoda family, with over 450 species divided into 33 genera. The members of the family share specific qualities. They have a flattened body, exterior surfaces, and have adapted to being surrounded by blood and mucus on their hosts' epithelial cells.

Planktonic Copepod

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Planktonic Copepods that live in the water play a vital role in world ecology and the carbon cycle. In the ocean and freshwater, they are usually the dominating members of the zooplankton and are key food animals for small fish such as the dragonet, banded killifish, and other crustaceans such as krill.

Habitat

Copepod populations live in settings with salinities ranging from virtually pure water to >35 parts per thousand. They can survive temperatures ranging from 10 to 28°C, as well as the water of dubious quality.

Individual animals of G. imparipes, for example, can endure a wide range of salinity variations. They can survive in temperatures ranging from 6°C to 28°C and can go without nourishment for long periods of time. Adult copepods can store energy in vast lipid reserves and survive for long periods of time without eating. Embryos are protected by being carried until they hatch into free-swimming nauplii, and parental investment of food reserves in the embryo increases the survival rate of juveniles. Many copepod species are hardy enough to tolerate the rigours of home gardening, as evidenced by this.

Movement

Many calanoid copepods have two separate movement styles. The force produced as the second antenna sweep at high frequency creates a smooth, gliding, swimming action. This motion serves as both feeding and a swimming motion. When swimming, the body is usually kept at a 45-degree angle to the horizontal.

As the animals ‘row' with their five pairs of legs, they travel faster through the water, resulting in quick jerky movements across multiple body lengths.

Body Size

Copepods in the first nauplius stage measure 125 metres in length and 65 metres in width. By N6, these have grown to a length of 310 metres. The length of the prosome is the most convenient size description for copepods and adults. Prosome lengths in adult G. imparipes range from 750m to 950m, depending on the temperature at which they originated. The pace of growth is slowed towards the low end of the tolerated temperature range, as it does for other invertebrates, and the final body size of adults is bigger for those raised in cooler water than for those raised in warmer water.

Nutritional Content

In the nutrition of larval fish, not all copepods are equal. To maintain the normal development of their neural system, larval fish require a diet rich in long-chain unsaturated fatty acids (HUFAs). Phytoplanktons create these HUFAs, which are not manufactured by vertebrates. Copepods that have been well-fed are likely to have stocks of these HUFAs, making them advantageous in fish diets. Copepods that graze on debris or prey on ciliates or rotifers have a higher amount of fatty acids in their reserves, which were generated by bacteria rather than phytoplanktons. Copepods have a lower nutritional value than larval fish.

Copepods, which store a lot of lipids and carry embryos in a clutch, have a higher value as a food item for fish if they eat the right phytoplanktons. Adult females with fresh algal food in their guts, lipids in storage, and eggs growing in their reproductive systems will make up a healthy population of phytoplankton-enriched copepods. According to studies, feeding fish preferentially select these enriched creatures.

In terms of the number of species and total biomass, three copepod groups dominate. They are calanoids, harpacticoids, and cyclopoids.

Calanoids

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The most abundant copepod group in the marine environment is the herbivorous calanoids, which are mostly barrel-shaped. Calanoid copepods are more abundant in the ocean (by weight) than any other planktonic animal group. Calanoids are almost always completely planktonic. The calanoids are the largest of the three major copepod groups in terms of physical size. They also have a jerky swimming motion that attracts young fish. Smaller naupliar size ranges are better for this, as only the tiny larvae with the tiniest mouths will be able to consume them. Calanoids are especially noteworthy because of their potential as live feed for a variety of suspension-feeding zooplanktivores due to their mostly pelagic lifestyle. Calanoids are widely thought to be the most difficult of the three major groups to culture in large quantities.

Harpacticoids

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Harpacticoid copepods have a longer body form than the other groups. Harpacticoid copepods are pelagic as larvae, but as adults, they settle onto the substrate and adopt a benthic existence. They are mostly detritivores, but they will happily consume any microalgal films they come upon. They are the hardiest of the three types, as well as the most adaptable to aquarium circumstances. As a result, they are the most likely to establish breeding populations in captivity. Feeding attempts with the harpacticoid Tigriopus have been positive, despite the fact that it is not utilized as frequently as the calanoids for larviculture.

Cyclopoids

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Cyclopoid copepods are characterized by their very big and well-developed primary antennae, in addition to a pear-shaped body that ends in a highly forked tail. They are real omnivores, eating everything from small particle organic materials to water column bacterioplankton. Cyclopoids like to live in enclosed or semi-enclosed pools of water, where they have evolved many adaptations to withstand drought and frost, making them highly hardy. They can be found in both freshwater and saltwater (some species can live in both). Although there are benthic variants, the majority are fully pelagic. They are often on the smaller side. They make up for their lack of physical size in terms of output. Over the course of a lifetime, females can generate 13 pairs of egg sacs (each containing about 50 eggs), resulting in a large number of offspring.

Freshwater Copepods

Copepods are one of the most popular aquatic live food products. This is due to the fact that they are a very nutritious species and are easy to feed to a variety of fish.

Young fish eat a lot of copepods when they're young. Copepods that live on their own are omnivorous. Phytoplankton and other tiny plankton are their main sources of food. Copepods in freshwater aquarium are also surviving.

Because our freshwater copepods are cultivated and harvested in tanks without fish, there is no risk of fish-borne or transmit viruses, bacteria, or fungal illnesses in the tank. These copepods have been multiplying for almost a year, beginning with a small lab-raised colony.

Copepods in Aquarium

Why Add Copepods to a Freshwater Aquarium?

Scavengers, many freshwater copepods graze on debris, bacteria, and algae. Our live aquarium copepods, both marine, and freshwater are popular among professional aquarists, breeders, and hobbyists who are seeking to retain difficult species such as the mandarin dragonet, scooter blenny, clownfish fry, dotty backs, bettas, and others.

Hobbyists who desire to breed both marine and freshwater species in captivity love them. This has been our goal since the beginning: to allow fish owners to breed the fish they want and sell them to other people who are interested in them without destroying the natural environment of these colourful and unique aquariums.

A single aquarium copepod may devour anywhere from 11,000 to 373,000 diatoms in a single day, making them an excellent tool to utilize in conjunction with rotifers to control a diatom outbreak in the aquarium.

Choose a Phytoplankton Source to Feed the Copepods.

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Phytoplankton can be obtained through a variety of methods, including home growing. Phytoplankton from a store will be more concentrated than phytoplankton generated at home. DT's Live Marine Phytoplankton, Reed Mariculture's Plankton Live FeedDiet, and a standard 2-liter bottle of home farmed phytoplankton are shown here. To avoid contamination and deterioration, utilise whatever source you choose and follow the instructions carefully.

Copepods prefer Nannochloropsis phytoplankton. Others may function just as well or better, but Nannochloropsis is commonly available, both commercially and from home gardens.

We need to fill the culture tank with a suitable amount of phytoplankton once we have it. I usually fill the tank less than half full to avoid spilling and part of the mess.

Not yet, but we have the culture tank full and ready for copepods. We must ensure that the culture tank parameters are within acceptable limits.

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• Temperature - We don’t use a tank warmer when growing copepods. With room temperature, it was good. So, what will be the temperature of the room? It refers to a room that is generally thought to be relaxing. This does not include the room on the northwest side of a house on the plains of North Dakota in January that had no insulation.

• Salinity - It's better if the culture tank and the feeding tank are the same size. This reduces the chance of copepods suffering from salt shock.

• Airflow - We can set up the airflow once the culture tank is filled with phytoplankton. This does not have to be a vigorous movement, but it must provide some circulation. Adjusting the airflow to a velocity slow enough to count the bubbles was sufficient for me.

• Lighting - Low-wattage fluorescent lighting or ambient room lighting

Adding the Copepods 

We can now add the copepods if all of the above has been accomplished satisfactorily. When adding the copepods, make sure the water conditions are similar to those in the culture tank. If not, attempt to gradually “acclimate” them, as they are fairly robust. The usual acclimatisation techniques will suffice.

Conclusion

From above we can conclude that Copepods are present in most aquatic habitats, ranging from the water bodies of Bromelia leafs over ground water reservoirs and benthic habitats to the vast three-dimensional space of lakes and oceans. Clearly we can say , not all Copepods  (even of the same order) are the same. A balanced mix of pod species is therefore excellent (particularly in a reef aquarium, which contains a wide diversity of organisms from all over the world). This will provide enough size, behaviour, and nutrition diversity to meet the needs of most aquarium cattle.