Characterization of haemocytes of the Indian edible oyster, Crassostrea madrasensis (Preston)

The haemocytes of the Indian edible oyster Crassostrea madrasensis were characterized using light and electron microscopy. The light microscopic study was conducted by staining a monolayer of the haemocytes with Geimsa. Cells without granules and with a large nucleus occupying much of the cytoplasmic area were grouped as hyalinocytes. Those with lesser amounts of basophilic cytoplasmic granules were characterized as semigranulocytes and those with large amounts of a mixture of acidophilic and basophilic granules were termed as granulocytes. Ultrastructural studies also revealed the presence of three types of haemocytes. Scanning electron microscopic studies were used to study the spreading behaviour of the haemocytes. Cytochemical studies revealed the presence of acidphosphatase, peroxidase and prophenol oxidase in the cells.     

Indexing serum biochemical attributes of Lutjanus argentimaculatus (Forsskal, 1775) to instrument in health assessment

The present study was aimed to establish reference data for nine serum biochemical attributes (glucose, protein, albumin, globulin, albumin/globulin ratio, cholesterol, triglycerides, serum glutamate oxaloacetate transaminase [SGOT] and serum glutamate pyruvate transaminase [SGPT]) of a supreme aquaculture candidate, namely Lutjanus argentimaculatus. Further, the influence of ecotype (cage–wild), condition index and gender on biochemical attributes was evaluated. The results have shown that gender and condition index had no significant effect in the studied age group, whereas ecotype had a significant role, except on serum glucose levels, suggesting the prime importance of estimating ecotype‐specific reference intervals for interpreting fish health. Intra‐ecotype variability of serum biochemical attributes, namely serum protein, globulin, cholesterol and triglycerides, was less, suggesting the possibility of using these parameters as health indices within a specific ecotype. Consistency in terms of the least intra‐ecotype variability coupled with PCA results points serum protein as the best ecotype‐specific health index among the different parameters studied. Altogether, the results of the present study provide thought‐provoking insights on serum biochemistry of L. argentimaculatus as a platform for the health management of this supreme aquaculture candidate.     

Mortalities caused by the crustacean isopod, Cirolana fluviatilis, in tropical, cage-cultured Asian seabass, Lates calcarifer: a case study from the southwest coast of India

Recurring mortalities inflicted by the cirolanid isopod Cirolana fluviatilis in the juveniles of the Asian seabass, Lates calcarifer , stocked in a cage farm in the Cochin backwaters, from November 2006 to May 2007, were investigated. Hatchery-reared fingerlings (size 8–12 cm) were cultured in floating cages and mortalities were observed after a rearing period of 1 month. The fish were found dead in the cages, with only the remnants of fish skeleton and all the flesh eaten away. Investigations revealed a very high abundance of isopods, identified as C. fluviatilis (Crustacea, Malacostraca, Isopoda and Ciroloanidae). During the first 2 months of stocking, 35% of the fingerlings died, and the cumulative mortality reached 45% in 6 months, considerably reducing the profits from the venture. Management measures for the control of the isopods are discussed. This is the first report on the isopod, C. fluviatilis , inflicting serious mortalities in a tropical cage-rearing system in the southwest coast of India.     

Ultrastructural changes in the hepatopancreas of Penaeus monodon Fabricius 1798 given aflatoxin B1 diets

Fungal contamination of shrimp feeds affects the shelf life leading to substantial economic losses. Ultrastructural changes in Penaeus monodon sub‐adults fed three different doses (50, 1000 and 2000 ppb) of aflatoxin B₁ (AFB₁) were studied. At the end of 4 and 8 weeks of experiment, the hepatopancreas of shrimps were observed for ultrastructural changes. The prominent ultrastructural changes in hepatopancreas of the shrimps fed 1000 and 2000 ppb AFB₁ were rupture of cell membrane and microvillus border, damage and swelling of mitochondria, fragmentation of endoplasmic reticulum, nuclear vacuolation, chromatin condensation and autophagy. This study helps to decipher the ultrastructural changes and relate the effects on biochemical, pathological, immunological and histological architecture of the shrimps fed AFB₁‐incorporated feed. The observed ultrastructural changes could serve as indicators in shrimps exposed to toxicants.