Artemia culture

We use Artemia salina larvae as the food for Clytia (both polyp and medusa). Olnly 1.5~4 dph (days post-hatching) larvae, instar II to instar IV stages, are appropriate as the food. Younger larvae, especially newly hatched instar I nauplii are not digestible by polyps and kill them, when used several days. (Occasional use of instar I is OK.)
To have appropriate quality of artemia every day. I recommend to start artemia culture three times a week.

Materials.

  • Artemia dried eggs (available from aquarium shop)
  • A tall plastic bottle with pointed bottom and valve. (A separatory funnel is good)
  • Air pump and tubing with sold plastic pipe at the end.

Procedure

The timing of schedule is indicated to make T=0 for the day of hatching (= dph days post-hatching).

Setting up culture (T = -1 day)

Put 1~2 ml (depends on requirement) of artemia eggs in the and add SW (~1 liter). Put the aeration tube in the tank. Make sure that the end of the aeration tube comes to the bottom otherwise eggs stay at the bottom of the funnel. keep the funnel in 30°C otherwise warm the culture with a lamp etc.
hatching_tank.jpg

Collecting newly hatched instar I larvae (T=0)

Separate hatched artemia from cysts and unhatched eggs. This process must be done within the day 0 ( when the it is in instar I stage) because instar I larvae go to the bottom of the funnel while most of cysts come to surface or are attached to the side of the funnel. Separation will be harder in later stages because both cyst and artemia lavae come to surface.Take the aeration tube out of the funnel slowly not to distrub the cysts attached to the side of the funnel. Wait for 5~10 minutes until artemia larvae comes to the bottom. Open the valve of the funnel to take settled artemia larvae to a small beaker (normally 20~50 ml). Wait another 10 minutes to collect artemia as much as possible (repeat a few to several times). Artemia suspension still have a bit of cysts. In order to separate perfectly, put them in a flat dish and light it from the side. Artemia basically moves to the side of the dish. You can easily separate artemia by a pipette from cysts. Separated artemia will be transferred to a large beaker with clean sea water and keep at 18°C with good aeration.

Using larvae (T= 1.5 days)

It is highly recommended to use older Artemia larvae (T=1.5~4 days).
Temporarily stop aeration of the beaker for Artemia stock (see above) and wait for a few minutes. Artemia will be concentrated by phototaxis. Then collect a part of them to a smaller beaker as an immediate stock and wait their phototaxis. Now the artemia is ready to be used as food. No areation is necessaly when they are stored at low density.

Organizing schedule

Here is an example of Artemia culture schedule. 1/2/3 indicate the lot of Artemia.

Mon
Tue
Wed
Thu
Fri
Sat
Sun
Culture Start
Culture 1 start

Culture 2 start

Culture 3 start


Instar I selection

1

2

3

Use
3
3
3/1
1
1/2
2
2/3
Discard


3

1

2