Shellfish Breeding and Hatchery Management (2+1)

18.2.3 Artemia and Shell Free Artemia for larvae

1. What is Artemia?

It is a micro crustacean or small crustacean just like shrimp or prawn (but very small in size) so that they can be used as the feed for the larvae of prawns,shrimps, crabs and any fishes.

2. Why it is to be used as larval feed?

Because it is very rich in protein, which is 100% digestible for any aquatic organism (fish or shrimp or prawn or crab). The biological value of the protein is similar to that of fish or prawn or shrimp and therefore this stands as the first preferred feed for the larvae.

It contains more vitamins and minerals in bio form that can be used by the larvae.

The first feed of the larvae is very critical. It must be good enough to sustain the life of the larvae. Therefore it is considered as the best suitable feed for the aquatic organisms.

3. For which this is used as the live feed?

For all aquatic organisms – like, shrimp, prawn, fish, crabs, lobsters, etc particularly the aquatic organisms that prefer or need only animal matter for its feed. Or we can say that all aquatic animals having carnivorous feeding habit can be fed with this

4. What are the advantages of Artemia?

1. It is a live feed – that is available as cysts which can be stored for a long period (may be 100 years if not hydrated)
2. The hatched out cysts will release nauplii, which care tiny and suitable for the mouth size of the larvae.
3. More of protein and other nutrients –except vitamin C
4. Available in more safe form – free from any bacterial load
5. They are readily available as cysts, which can be used for producing the nauplii in the hatchery.

5. What is shell free Artemia?

The Artemia is available as cysts – i.e. eggs produced under unfavorable conditions from which the organism can come to life once the situations are very favorable to them. These cysts are very hard materials that they have a strong epi coat over their cysts. Thiepi coat can resist to any intolerable conditions even to acidic conditions.But they can absorb water and be hydrated. The real Artemia is inside this epi coats developing nauplii but in inactive form until it touches the water of favorable quality. Most of the aquatic organisms can not digest this epi coat and therefore they can not use this Artemia nauplii unless until the epi coais removed or hatched out. Therefore forgetting the Artemia nauplii the cysts must be hatched out through the Artemia hatching process, which is cumbersome and will take about 24 hrs.

Considering the cumbersome process of hatching, which requires seawater, light, aeration and correct pH to make them hatching up to 85% now many hatchery operators are using the Artemia cysts as such after decapsulating them or removing the epi coat over the nauplii. This process is called Decapsulation of the cysts there by the epi coat is digested and removed from the cysts. This will make the cysts readily usable by the larvae or fry.

Until very recently the cysts are available as cysts and used for hatching and nauplii production. But after careful thought and bio processing, now the epi coat is removed and available as Shell Free Artemia which do not have the shell or epi coat over them. This is called Shell Free Artemia.

6. What are the advantages of Shell Free Artemia?

1. The shell free Artemia is a ready to use product – that means it does not require any hatching
2. During hatching not all cysts will hatch out. The maximum possible hatching percentage is only 90% - that means – out of 100 cysts only 90 cysts alone can be used in the case of normal cysts. But in Shell Free Artemia all the 100 cysts (i.e. 100%) can be used.
3. There is no requirement for hatching – that means no need for electricity expenses or aeration or seawater.
4. On hatching the nauplii will start using the stored up energy (i.e – yolk) so that ultimately there is an energy loss as per the energy pyramid. In shell free Artemia there is no loss in energy and the total energy stored up in the cysts will be delivered to the target organisms.
5. There will be chances for the infection through the nauplii once they are hatched out in the seawater. In the Shell Free Artemia, no such infection as the cysts will not touch the seawater.
6. More importantly the Shell Free Artemia can be used as a ready to serve feed in the hatchery thereby it reduces the risk ok non-fed conditions arising due to non-availability of nauplii.