Acetylcholinesterase (AChE) activity is a well-known biomarker for exposure to organophosphate or carbamate compounds in aquatic organisms. However, the effect of dibutyl phthalate (DBP) and di-ethylhexyl phthalate (DEHP), widely used as a plasticizer, on the change of AChE activity is not yet known. Bagrid catfish Pseudobagrus fulvidraco were administrated with 100, 500 and 1000 mg kg )1 diet of DBP or DEHP and the effects on AChE activity were assessed in the liver, gill, kidney, heart, brain, muscle and eye of the exposed fish. All tissues contained different background AChE activity in non-treated bagrid catfish: the highest was observed in the brain, followed by muscle, heart, and kidney. The enzyme activities in various tissues were significantly inhibited after exposure to DBP or DEHP in a concentration-dependent manner, especially in brain and muscle. A similar, but less pronounced, inhibition was also observed in liver and kidney when exposed to DBP and DEHP. Although AChE activity in gill and heart was also affected by DBP and DEHP, the decrease in these organs was least marked in these organs. Exposure to 1000 mg kg )1 led to mortalities of 8.0% with DBH and 14% with DEHP; both seemed to be ascribable to phthalate toxicity. This study is the first report that the measurement of AChE activity in bagrid catfish is a valuable biomarker of DBP and DEHP exposure. This biomarker could be incorporated into a battery of biomarkers to strengthen the confidence with which ecotoxicologists can assess the impact of phthalate ester pollution in the aquatic environment.

This study investigated the e¡ects of di¡erent types of diet and sediment on the growth parameters of juvenile tiger crab Orithyia sinica under laboratory conditions, focusing on survival, growth and moulting. In the ¢rst set of experiments, juvenile tiger crabs were reared with ¢ve di¡erent types of sediment, i.e., soft sand, coarse sand, soft sand mixed with coarse sand, mud or bare bottom. Soft sand resulted in not only the highest survival rate of 78% but also the best rate of growth and feed intake. Crabs reared with a mud substrate showed the worst results in these parameters. The intermoult period, however, was not affected by sediment types. In the second set of experiments, crabs were fed di¡erent types of diet to determine their e¡ects on the same growth parameters. Diets were composed of di¡erent combinations with Manila clam (Ruditapes philippinarum), brine shrimp (Artemia nauplii), microencapsulated feeds and marine diatom (Chaetoceros gracilis). Survival and growth in crabs fed Manila clam as a diet component were signi¢cantly higher than in those on other diets. The highest survival and growth were achieved with a diet that included all four components. These results provide valuable information on the appropriate bottom substrates and diet types necessary for arti¢cial mass culture of the tiger crab.