Feeding of milkfish (Chanos chanos) larvae and juveniles on Artemia nauplii in captivity was observed. The retinae of the larvae were observed histologically. Milkfish larvae could not take food in the dark. The juveniles could take food in the dark although less efficiently than in the lighted condition. Vision thus seems to be the most important sense for the milkfish larvae since feding depends very much on it. The larvae were found to have already well-developed regionally differentated retinae with all elements present. Vision, evidently, is developed foremost among the senses.

The study was conducted to study the effects of single injections of Human Chorionic Gonadotropin (HCG) (Ayerst Laboratories, Inc) and Durandron Forte 250, a long-acting androgen preparation (N.V. Organon Oss, Holland), on sperm motility, vitality and density and on the consistency of milt in newly caught, wild, mature milkfish (Chanos chanos). There is an advantage in using Durandron Forte 250 in inducing thinning of milt in mature milkfish during the natural breeding season to facilitate fertilization of eggs. Aside from its long-lasting effect which minimizes handling of fish, it is much cheaper than HCG.

This is the first report in the world on the characters of the first zoea of Calappa philargius under laboratory conditions. The zoea has a rostral, a dorsal and a pair of lateral spines on the carapace. The average length of larvae from tip of rostral to tip of dorsal spine is 1.26 mm, width, including both lateral spines, 0.74 mm and that of distance between outer margins of eyes, 0.47 mm. There are a pair of lateral hooks on the second and third abdominal segments. There are four natatory hairs on the first and second maxillipeds. Spinal arrangements on the endopodites of the first and second maxillipeds from proximal to distal segment are 2-1-0-2-5 (or 4) and 1-1-4 (or 3), respectively. The number of inner setae on the telson is six (3+3).

This paper describes a method of constructing 12 mm thick ferocement buoys used as a floatation system in the culture of green mussels (Mytilus smaragdinus).

A female milkfish, captured at sea, was injected with two hormonal injections of acetone-dried salmon pituitary powder and human chorionic gonadotropin, plus Vitamin B complex. It was stripped, and produced 128,000 ripe eggs with an average diameter of 1.15 mm. Fertilization rate was 38% following artificial fertilization with milt from an uninjected male. A total of 36,000 larvae hatched (74% of fertile eggs) after 26–32 h at 34 ‰ salinity and 27–32°C. The newly hatched larvae measured 3.4 mm in mean total length and possessed a large yolk sac. The mouth of the larvae opened about 54 h after hatching. The larvae were fed with fertilized oyster eggs, rotifers, copepods, brine shrimp, flour and prepared feed, together with Chlorella. A critical period was between the 4th and 6th days with mortality over 80%. The larvae started increasing in length by Day 8, and had the appearance of the wild fry by Day 11. On Day 13 a pigmentation pattern developed and the biggest larva measured 10.0 mm. By Day 18 the larvae measured 12.5 mm, and 14.5 mm by Day 21. A total of 2,859 fry was obtained; the highest larval survival rate obtained from different experimental groups was 46.8%.

The egg, larval stages and the first postlarva of the giant tiger prawn, Penaeus monodon Fabricius, reared from egg in the laboratory are described and illustrated. Six naupliar, three protozoeal and three mysis stages are recognized. The larvae of P. monodon are morphologically similar to those of P. japonicus described by Hudinaga except for the following characters: 1) number of setae on first antenna of fourth and fifth nauplii is 5 or 6 in P. monodon, but it is 7 in P. japonicus; 2) supra-orbital spine of second protozoea is bifurcated at base in P. monodon, but at tip in P. japonicus; 3) number of segments of endopod of second maxilliped of second mysis is 5 in P. monodon, but it is 4 in P. japonicus; 4) number of rostral spines in second and third myses is 0 and 0 or 1 respectively in P. monodon, but it is 1 and 2 respectively in P. japonicus.

A phycomycetous fungus, presumably a Lagenidium, was observed to infect Penaeus monodon larvae. Monitoring of the hatchery in 1976 and 1977 showed that it occurred in 35 out of 51 and 22 out of 37 runs, respectively. So devastating was the infection that whole tank populations had to be discarded after 48 hr. Extramatrical tubes are sent out profusely; a discharge vesicle is formed from each tube. The cytoplasmic contents of the hypha then flow into the vesicle, and zoospore formation occurs. Zoospore release is facilitated by rupture of the vesicle after continuous movement of the zoospores. The hyphae in infected larvae measure 2.5-6.3 microns wide. The discharge vesicles are 14.5-25.0 microns in diameter; each one releases 14-32 zoospores 3.8-6.3 microns wide by 5.0-6.3 microns long.

Courtship and mating behavior in the sugpo or giant tiger prawn, Penaeus monodon Fabricius, are described. These are divided into three phases: parallel swimming of male and female; male turns ventral side up to female; and, male turns perpendicular to female, curves body around female and flicks both head and tail. Comparison with observations on P. japonicus and P. stylirostris is made.

Hydrated eggs obtained from a female milkfish, Chanos chanos, were artificially fertilized with the milt collected from a male injected with acetone-dried pituitaries of salmon. The fertilized eggs (1.1–1.25 mm in diameter) developed normally in seawater in basins and petri dishes at a salinity of 30–34‰, and successfully hatched in 25–28.5 hours at a temperature of 26.4–29.9°C. The yolk was completely absorbed in about 2.5 days and during this period many postlarvae died. A few larvae were reared up to 5 days but all died on the 6th day. Attempts were made to feed the postlarvae with freshly hatched trochophore larvae of oysters obtained from eggs artificially fertilized in the laboratory.