8/10/2019 Rearing the Flying Fish

1/3

Larval rearing of flying fish (Family: Exocoetidae)

Binu VargheseProgramme Manager, Marine Products Export Development Authority

Kochi, India

bvargheseb@gmail.com

During sea cruises flying fishes attract our attention with their gentle gliding movement

just above the water surface. These fishes were reported to have mass spawning activitywith many pairs using same floating substrate to attach their eggs. The drifting

Sargassumweeds attached with egg mass of flying fishes were collected from Vizhinjamcoast (Southern India).The eggs were perfectly camouflaged with the sargassum weeds as

if to appear as the air bladders in Sargassum (fig. 1). The egg mass was carefullytransferred to a 250 liter aerated aquarium and hung in the water column to allow

movement as well as circulation between the densely packed eggs. The salinity of waterwas maintained at 32 ppt, pH at 8.1 and temperature 281 C.

Fig. 1. The egg mass of flying fish

The egg was spherical with a diameter of 2.4 mm. They were clubbed together and

attached firmly to the seaweed with numerous thin filaments. Close observation of eggsrevealed fully developed embryo moving inside (fig. 2).

.

Fig.2. Egg with fully developed embryo

8/10/2019 Rearing the Flying Fish

2/3

Immediately after transfer many small wrigglers were found on the bottom of the tank.These newly hatched larvae were comparatively large with 7.0 mm and had hefty yolk-

sac (fig.3a). This heavy yolk reserve made them occupy the bottom of aquarium with atypical wriggling movement (fig. 3b). The hatching process continued for a few days

suggesting the eggs to be part of mass spawning activity. Even after three days several

unhatched eggs were found attached to the substrate.

Fig. 3a. The newly hatched larvae (wrigglers)

Fig. 3b. Newly hatched larvae with the yolk-sac

The larvae were transferred to two FRP tanks with recirculation provided with gentle

aeration. The yolk lasted for about 4-5 days and by then they were readily feeding on theArtemianauplii. The larvae developed into strange shapes with rounded fins and swarm

near the surface (fig.4).

Fig. 4. Intermediate fry stage with rounded fins

Most amazingly in this early days itself larvae had the ability to glide over the watersurface. Showing their true character even the week old larvae glided over the water

8/10/2019 Rearing the Flying Fish

3/3

surface whenever their movement is obstructed. The larvae were fed with artemia naupliiimmediately after yolk absorption.

Gradually the body shape and the fins changed into adult form (metamorphosis) with the

typical elongated and expanded fin structures. After this change they rapidly gained

momentum and started hitting the side walls which caused heavy mortality. Subsequentlyfries were released after a months growth back to the Vizhinjam Bay.

The length and weight of fries recorded

Length (mm) Weight (mg)23 68.1

20 43.717 32.9

17

32.8

2013 All rights reserved.