The manual provides information on the diseases that affect the 3 major species of shrimps culture in the Philippines: Penaeus monodon, P. merguiensis and P. indicus. It includes the common name of the disease, causative agent, species affected, stages affected, gross signs, effects on the host and methods of prevention and treatment.

Details are given of factors to be taken into account for successful hatchery operation. The following aspects are covered: 1) site selection; 2) hatchery design and construction; 3) life cycle; 4) preparation of broodstock for spawning; 5) larval feed; 6) spawning, hatching and larval rearing facilities; 7) spawner selection and egg collection 8) nauplii hatching and transportation; 9) larval rearing; 10) routine hatching, management; 11) port-larvae nursery; and 12) larval harvesting and transportation.

Eight typical devices and gears for catching the wild fry of the giant tiger prawn, Penaeus monodon, locally called sugpo are described and illustrated. There are three stationary ones vis. fry lure, fry filter net and set fry trap, and five mobile ones viz. scoop net, fry scare line, fry seine, triangular net, and fry bulldozer. These have been used traditionally in the Philippines. This design and manner of operation are adapted to the behaviors and habits of the sugpo fry such as clinging and incursion with the incoming tidal current in mangrove creeks or at the mouth of the brackish river.

The manual is intended as a guide for operation in milkfish farming. It is presented under the following major sections: 1) Handling of fry - counting, storage and transport; 2) Pond layout and construction - selection of farm site, layout, construction, plan and specification; 3) Pond operation, culture and management - nursery pond management and rearing pond operation; 4) Harvest and post-harvest - harvest, post harvest, and processing; and 5) Economics and costing - cost of construction, cost of operation, and production/yield.

The need for a chemotherapeutant used specifically for fish disease became increasingly apparent with intensive fish culture practices, and with the possibility of bacterial resistance against drugs used for human and animal medicine (Austin 1985). With this in mind, Nifurpirinol (trade name Furanace; P-7138) was developed by the Dainippon Pharmaceutical Co., Ltd., Japan, and is currently manufactured in the United States as Prefuran. Studies have proven that the drug is effective against bacterial and fungal pathogens in a wide variety of aquatic animals. Most of the Nifurpirinol studies done in the past have dealt on its antimicrobial activity, tissue uptake, and effective treatment levels ranging from 0.5-2.5 mg/L. The 96-hr median lethal concentration (LC50) to channel catfish (Ictalurus punctatus Rafinesque) has also been determined at 0.945-1.90 mg/L, and at 1.70 mg/L for milkfish, Chanos chanos Forsskaal. However, there have only been two studies that have examined the histological effects on treated fish. Histopathologically, Mitchell et al. (1978) found hypertrophy and hyperplasia of the lamellar epithelium in channel catfish gills exposed to 0.5 mg/L for 4 d or longer at 24 plus or minus 2 degree C, while Amend and Ross (1970) working at 21 plus or minus 1 degree C observed no apparent changes in the gills of coho salmon (Oncorhynchus kisutch) exposed intermittently to 1 mg/L of Nifurpirinol. This paper describes the histological changes observed in the gills of milkfish fingerlings used in static, 96-hr Nifurpirinol toxicity tests. Milkfish was used because of its economic importance as a widely cultured food fish in Asia. The gills were chosen as target organs.

The most economical combination of dietary protein and feeding levels for milkfish culture in brackishwater ponds was determined. Milkfish juveniles (average weight, 5 g) were stocked at 7000/ ha and fed two diets containing 24% or 31% dietary protein at 2 or 4% of body weight. There was no interaction between feeding level and dietary protein on growth, feed efficiency, and energy assimilation of milkfish. This indicates that the response of milkfish to change in protein levels is not influenced by ration size. Regardless of protein levels, the final weight, weight gain, specific growth rate, and production of milkfish were significantly higher (α = 0.05) when fed at 4% body weight than at 2%. As culture progresses, differences in weights of fish fed varying protein levels were still insignificant. This could be attributed to the balanced amino acid profile of both diets. The higher growth at the 4% feeding level could be due to the higher amount of amino acids available for protein synthesis. Higher energy assimilated by milkfish at higher feeding rate demonstrates that energy supply also influences growth. Partial budgeting analysis shows that bigger profits can be earned by using a 24% protein diet with balanced amino acids at a feeding rate of 4% of body weight. The greater amount of feed given at higher rate can be compensated by faster growth and higher production.

The manual provides information on the culture of shrimps and prawns. Considerations regarding farm sites, pond specifications, pond ecosystems and differences between prawn and milkfish culture are examined. Seed supply, farm management practices and economic aspects are detailed.

Around 50% of mangrove loss in the Philippines can be traced to brackishwater pond construction. The decrease in mangroves from 450 000 ha in 1920 to 132 500 ha in 1990 has been accompanied by expansion of culture ponds to 223 000 ha in 1990. The history of fishpond development in the country includes a government-sponsored fishpond boom in the 1950-g and 1960s, the proconservation decade of the 1970s followed by a shrimp fever in the 1980s. Production from brackisshwater ponds has increased from 15 900 mt worth P7.6 million in 1938 to 267 000 mt valued at P6.5 billion in 1990. On the other hand, the maximum valuation of over $11 000 ha⁻¹ yr⁻¹ for unmanaged and managed mangrove forests makes them economically on par with the most profitable pond farming systems. The loss of mangrove systems and their varied goods and services is the single most important consequence of brackishwater pond culture in the Philippines. Moreover, intensive shrimp farming is associated with other ecological and socioeconomic effects such as pollution of coastal waters and decline in domestic food crops. New legislation and enforcement of existing laws, conservation of remaining mangroves, massive rehabilitation of denuded mangrove areas, and promotion of sustainable aquaculture and fisheries are recommended.

Disease in prawn is any abnormal condition which may affect adversely the appearance, growth, and function of the animal. It may or may not result in mortalities. Disease outbreaks occur commonly in different culture systems such as hatcheries and grow-out ponds. Disease develops through the interaction of the prawn (the host), the causal agent (the pathogen), and the environment. In the presence of a susceptible host, a pathogen and predisposing environmental conditions (poor water quality, inadequate food, frequent handling, overstocking), disease is very likely to occur. Improved environmental conditions, healthy prawns and absence of disease agents would therefore lessen the chance of a disease outbreak. The causal agents may be pathogenic organisms (viruses, bacteria, fungi, protozoa, helminths, microcrustaceans) or nonpathogenic adverse environmental conditions (extreme temperatures, low oxygen levels, chemical poisons). Living disease agents cause infectious disease which generally result in gradual mortalities. Non-living disease agents cause non-infectious diseases that result in sudden mass mortalities. The environment determines the balance between the prawn as host and the disease agent. Microorganisms are always present in the water and some of them cause disease only when the prawn has been weakened through exposure to stressful environmental conditions. Hatchery personnel should realize that they themselves could transmit disease through their contaminated hands, clothing, and footwear. Equipment such as water pumps, blowers, pipes, and materials such as scoop nets, water hoses, pails, glasswares are also possible carriers of disease agents. Spawners, live natural food like diatoms, rotifers and brine shrimp, and artificial diets could also be vehicles of disease transmission. The prawn culturist, thus, must be able to manage the environment and make it favorable for the prawn. Hatchery management should, therefore, include operation procedures that will reduce the possibility of disease development during larval rearing. This manual recommends practices for disease prevention to prawn hatchery operators and technicians.