Swim-up Fry


Tilapia Swim-up Fry

What is a swim-up fry?

Eggs are harvested from the mouths of brooding females and incubated artificially in the hatchery at Nam Sai Farms. They take up to 3 days to hatch into sac fry and continue to feed on the yolk sac for another 5 days before developing into swim-up fry. At this stage they swim to the water surface to seek out food, hence the name swim-up fry. Eggs and sac-fry must be kept in continual motion in incubators and trays for them to survive. For this reason they are not suitable for transport. Swim-up fry, however, are able to swim and find food and can be transported long distances very successfully.

Why Purchase Swim-Up Fry & Not 1” Monosex?

1. They are kept in a recirculating hatchery system with very stable water quality and protection against disease. This ensures good survival every time and reduces the risk of disease transfer.

2. Swim-up fry have yet to be fed and so there is no problem with ammonia build up in the bags during transport.

3. Swim-up fry are only 0.008 to 0.009g per fish (compared to 0.2g for 1” fish), and this allows large numbers of fish to be packed per box (10,000 per box for trips up to 40 hours).

4. Swim-up fry with a little yolk sac remaining can be selected for long distance transport so the fish will not starve.

5. Swim-up fry can go into a hibernation-type state (if temperature is low) and this ensures that many fish will survive if there is a long transport delay, even up to 80 hours.

“Do-It-Yourself” Monosex Package

Swim-up fry are not yet sexually developed and will become mixed sex fish within a period of 22 days at 29ºC or more. Nam Sai Farms can supply sex reversal food and hapas for use in producing male monosex tilapia as part of a “do-it-yourself” package. This involves stocking 30,000 swim-up fry in a 5 m2 hapa suspended in green water (fertilized to create a plankton bloom). The fish are fed 5 times per day with sex reversal food for a total of 21 days. 4.9 kg of feed will be required to sex reverse 30,000 fish. One can expect from 99 to100% male yields by using Nam Sai feed and by following the correct procedure.

Swim-up fry can also be sex reversed in clear water in tanks, but the hormone concentration of the feed should be decreased and more food fed (plain fish meal can be added to our feed to do this). It is important that each fish gets a correct dose within a time period that is affected by temperature. More detailed information on the procedure will be provided to customers according to their rearing method once fish are ordered.

D-I-Y Prices:

Number purchased Price in Thai Baht Price in US$ per 100
Blacks Reds Blacks Reds
30,000 - 50,000 0.24 0.29 0.80 0.97
50,000 - 100,000 0.22 0.27 0.73 0.90
100,000 - 200,000 0.21 0.26 0.70 0.87
> 200,000 0.20 0.25 0.67 0.83
Minimum size of order = 30,000 fish (equivalent to a 5 m2 hapa requiring 4.9 kg of feed)
Please note: The prices quoted above are for use of swim-up fry as part of a sex reversal “do-it-youself” kit and not for growing as broodfish. Only hybrid stock will be provided, unless the broodstock fee is paid for a particular strain.

Hapa and feed:

No.of fish to stock Hapa size (m2) Sex reversal feed used (kg) Price of sex reversal feed
Baht $US
30,000 5 5 700 23.33
60,000 10 10 1,400 46.67
120,000 20 20 2,800 93.33
Baht/$US = 30
Please note that the prices are not inclusive of packing and transport and a quote will be provided on request (see export packing, transport and documentation). Most often the fish have to be put in a separate invoice from the hapas and feed, as they are a different category of freight. One way is to send the feed, hapas and other equipment (for example scoop nets) prior to sending the fish. This way advance preparations can be made before the fish arrive.