Determination of metabolic rates and quotients in fish

Before any growth can be,achieved by an organism there must be sufficient energy in the food to provide for the metabolic demands of maintenance and any activity associated with food intake. In culture practices it is possible to reduce these energy costs to a minimum and to optimize food conversion. This can be done through an understanding of the environmental and biological factors affecting metabolic rate with a view to reduce the demands on the system and hence increase the production. It is therefore desirable to examine the broad picture of energy exchange within an animal; then proceed to more specific considerations in fish. Since it is the principles and prospects which are of major interest here, no attempt is made to make this a major review of the subject

Transportation of live Finfishes and Shellfishes

Livefish trade, especially the live ornamental fish and live seafood trade, is emerging as a major business venture in most of the tropical countries. Production of livefish through aquaculture has also undergone vast changes during the past 20 years. In aquaculture, transport of broodstock from the wild to the hatchery or seed from the hatchery to the growouts forms one of the basic requirements. The demandfor livefiriflsh and shellfish is rapidly increasir^g and in most of the developed countries, more and more livefish traders and restaurants are offering live fishery products to their customers. Air liftiry of live se<^ood has also increased during the last few years. The mcgor constraint to the development of live seafood export is the lack of information on handling the aquatic organisms after they are caught, right through the transport and sale to the customers. Necessary precautions have to be taken while catching, packing and transporting the aquatic organisms. Apart from careful handling, a thorough knowledge of the behaviour and physiology of the animal is necessary to minimise the stress during storage and transportation

Status of feed management

Feed management is playing a vital role in aquaculture as half of the operational cost comes from feed. Great care must be taken unless the farmer will incur loss

Some investigations on the activity of phenol oxidase in the isopod Cirolana fluviatilis

Phenol oxidase activity in the isopod Cirolana fluviatilis averaged 0.0015 w.units/mg protein/min in the larger isopod.samples (10-17 mg) and 0.00034 O.D. units/mg protein/min in the smaller samples (6-9 mg). The enzyme showed equal affinity for epinephrine and dopamine and >5O% affinity for DOPA

Significance of farm-made feeds in the Indian context

The bulk of shrimp production comes from semi-intensive farming in the brackish water systems. The nutritional requirements of shrimpalong with their feeding in these systems is complex and poorly understood primarily due to the difficulties encountered in quantifying the contribution of naturally available food organisms

Histomorphology of the Hypothalamo – Neurosecretory System of the Indian Scad, Decapterus tabl (Berry)

Hypothalamo-neurosecretory complex of Decapterus fabl consists mainly of the nucleus preopticus (NPO), nucleus lateral is tuberis (NL T) and their zonal tracts. The neurosecretory cells of NPO are generally bipolar and stain readily with aldehyde fuchsin (AF) and chrom-alum -hematoxylin-phloxine (CAPH) but they are also positive to acid fuchsin in Mallory's triple stain. NPO is a paired structure situated on either side of the third ventricle antero-dorsal to the optic chiasma. It is highly vascularized structure and looks inverted L.-shape in the sagittal section

Branchial, renal and hepatic lesions in an estuarine mullet, Liza parsia Hamilton - Buchanan, induced by sublethal exposure to BHC

Gill of Liza parsia exposed to sublethal concentration (0.5 ppm) of BHC responded initially with the copious secretion of mucus followed by oedematous separation of epithelial lining cells from the basement membrane. Fusion of secondary gill lamellae, tissue hyperplasia and multiple telangiectases (aneurysms) were noticed on day 10 of the exposure. By day 15, the entire interlamellar spaces became filled with the hyperplastic epithelium. Kidney revealed an initial hypertrophy of the cells lining proximal convoluted tubules followed by shrinkage in the glomerular tufts resulting in the increase of Bowman's space and oedema. Tubulonecrosis, hyperemia and fibrosis were noticed in the reneal tissue after day 19 of BHC intoxication. Exposure to BHC elicited an initial dilation of bile canaliculi, enhanced secretion of bile and cellular hypertophy on day 4. Necrotic changes like excessive vacuolation, and karyorrhexis and karyolysis were seen on day 8. By day 10 and 15, complete vacuolation of hepatocytes, pycnosis of nuclei and focal necrosis were noticed

Histopathological changes in gill, kidney and liver of an estuarine mullet, Liza parsia, induced by sublethal exposure to DDT

Liza parsia were exposed to sublethal (0.02 ppm) concentration of DDT for 15 days. The gill responded initially with copious secretion of mucus, oedematous separation of epithelial cells from the basement membrane and fusion of secondary gill lamellae. Hyperplasia of the cells lining primary gill lamellae and lamellar telangiectases (or aneurysms) was frequently seen after day 10 of exposure. Kidney exhibited hypertrophy of the epithelial cells lining proximal convoluted tubules which was followed by shrinkage in glomerular tufts, increase in Bowman's space, appearance of amorphous eosinophilic materials in the lumina of the tubules and focal necrosis on day 10 of the treatment. Hyaline droplets and casts were also encountered in the epithelial cells and lumina of the proximal tubules. Liver revealed an initial dilation of canaliculi and increased secretion of bile. Thereafter, the displacement of nuclei towards periphery of the hepatocytes, disorganization of blood sinusoids, pyknotic changes in nuclei, cytolysis and vacuolation as well as focal necrosis were noticed after day 10 of the intoxication

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Neuroendocrine factors influencing maturation in shrimps

The females in the crustacean species have to cope up in the adult stage, with two highly energy demanding processes namely body growth and reproduction. Body growth and moulting are periodic events in the life cycle of prawns. In prawns reproduction and growth are programmed as antagonistic events. Apparently moulting is induced when the levels of moult inhibiting hormone (MIH) and gonad stimulating hormone (GSH) are low and gonad inhibiting hormone (GIH) and moulting hormone (MH) are high. To induce gonadal maturation and spawning, unilateral eyestalk ablation is the technique widely used nowdays