Seasonal changes in the blood parameters of two major carps, Labeo rohita (Ham.) and Cirrhina mrigala (Ham.).

Seasonal changes in blood properties of two Indian major carps, L. rohita and C. mrigala, were investigated. Haematocrit values, haemoglobin concentrations and erythrocyte numbers showed seasonal fluctuations, being high from September to November and again in April-May, and low from January to March. Males had generally higher blood values than the females.     

Use of RAPD fingerprinting for discriminating two populations of Hilsa shad (Tenualosa ilisha Ham.) from inland rivers of Bangladesh

The Random Amplified Polymorphic DNA-Polymerase Chain Reaction (RAPD-PCR) was applied to analyze the genetic variation of the Hilsa shad, Tenualosa ilisha Ham., from the two major inland rivers (Padma and Meghna) in Bangladesh. Twenty-eight random 10-mer primers were primarily scored in 8 individuals from each of the two locations. Fifteen primers, which gave polymorphism, were selected and used in the final analysis of 34 individuals from the two sites. Using these primers, 480 scorable DNA fragments were found, of which 98 (20.41%) were polymorphic. By comparing the RAPD banding patterns, variations were found between and within the populations. A dendrogram was constructed with the polymorphic fragments to analyze the genetic distances between the Hilsa shad populations. The results show two major clusters of Padma and Meghna, assuming different spawning populations with different stocks or races of Hilsa shad in the major Bangladesh rivers.     

A new species of the mazocraeid genus Cribromazocraes Mamaev, 1981, from the freshwater clupeid Hilsa ilisha (Ham.) from the Kanpur District,India

Cribromazocraes llewellyni n. sp. is described from a freshwater clupeid Hilsa ilisha (Ham.) from the Kanpur District, India. It is characterised by the presence of unbranched intestinal caeca, the number and arrangement of the genital spines, the shape of the clamp sclerites and the presence of marginal hooklets. This is the first record of the genus Cribromazocraes Mamaev, 1981 from India.     

The development of neuromasts in Cirrhina mrigala Ham. Buch. (Cyprinidae) and Ophicephalus (Channa) punctatus Bloch (Channidae)

The development of neuromasts was studied in two species of teleosts, Cirrhina mrigala Ham. Buch. and Ophicephalus punctatus Bloch, and the findings are presented and discussed. It has been discovered, in the course of this investigation, that a neuromast arises by a process of invagination — a fact hitherto not reported. The occurrence of the dorsal lateral line and the accessory lateral line of the trunk, in addition to the main lateral line, has also been reported for the first time for teleosts, although known for other bony fishes.     

Phosphorus requirements and optimum calcium/phosphorus ratio in the diet of mrigal Cirrhinus mrigala (Ham.) fingerlings

An experiment was conducted to investigate phosphorus requirements and the optimal calcium/phosphorus (Ca/P) ratio on growth and carcass tissue composition of mrigal Cirrhinus mrigala (c. 6 g). Five purified diets were formulated to contain Ca/P ratios of 1 : 0 (0.35 : 0), 1 : 1 (0.35 : 0.35), 1 : 2 (0.31 : 0.63), 1 : 3 (0.24 : 0.71), and 1 : 4 (0.19 : 0.75), respectively. Growth performance and feed conversion ratio of mrigal responded significantly (P < 0.01) to the Ca =0.19 : P = 0.75 diet. Carcass protein, lipid, and P percentage also increased significantly with the higher P level. Based on this study, it may be concluded under the given conditions that the optimum Ca : P ratio in mrigal feed is 0.19 : 0.75.     

Responses of isolated scale melanophores of a fresh water carp,Cirrhinus mrigala (Ham.) to zidovudine

Zidovudine (AZT) induced concentration related aggregation in C. mrigala melanophores. Denervated melanophores failed to respond to AZT. Specific and nonspecific alpha adrenoceptor antagonists completely blocked the responses of fish melanophores to AZT. Histamine and prostaglandin antagonists also inhibited aggregation of the melanophores induced by AZT. The results suggest that AZT may release a mixture of neurotransmitter like substances, which cause the aggregation of this fish melanophores.     

Habitat modelling of juvenile Hilsa Tenualosa ilisha (Clupeiformes) in the coastal ecosystem of the northern Bay of Bengal,Bangladesh

Hilsa shad Tenualosa ilisha comprises the largest and most valuable single fishery of Bangladesh. This study was conducted to identify suitable habitats for Hilsa juvenile in the northern Bay of Bengal along the coast of Bangladesh using Geographical Information Systems (GIS) based Multi-Criteria Evaluation (MCE) of water temperature, dissolved oxygen, pH, salinity, turbidity, current, depth and rainfall. Landsat imagery and 8 thematic layers were analyzed with ENVI and GIS capabilities, and developed as a series of GIS models to identify and prioritize the appropriate habitats for Hilsa juvenile. The study covered 29.484 km² water body and revealed that 56% (16.388 km²) is the most suitable, 21% (6.054 km²) is moderately suitable and 24% (7.042 km²) is not suitable which was consistent with field verification. The assemblage of marinebrackish-freshwater ecosystems with favourable ecological parameters and rainfall patterns are very much important for supporting juvenile Hilsa in the study area. The results are useful for habitat-specific sanctuary development as the efficient conservation may lead to higher production of adult Hilsa and increase the economic benefit to the fishers.     

Seasonal variations in the histology of the pituitary gland of Cirrhinus mrigala (Ham.) an Indian freshwater major carp, in relation to gonadal activity.

1. Seasonal variations in the histology of the pituitary gland of Cirrhinus mrigala (Ham.), an Indian freshwater major carp, in relation to gonadal activity has been studied during a one year period commencing, January, 1971. 2. The proximal pars distalis undergoes a great deal of seasonal variation in size, weight and nature of pituicytes. 3. The percentage composition of acidophils and cyanophils in the proximal pars distalis show a reciprocal relationship during the year. The acidophils predominate during the restitution phase of the gonads while the cyanophils preponderate among the different cell types during the breeding season. 4. The chromophobes do not show any significant fluctuation in numerical abundance in relation to gonadal activity. 5. Cyanophils of the proximal pars distalis undergo changes with change in gonadal activity Concentration of glycoproteinaceous material is extremely low during the restitution phase but high during the maturation phase. The cyanophils also undergo hypertrophy and hyperplasia during the spawning period. The latter discharge their contents and become vacuolated during the post spawning period. 6. The number and size of the globules in the cyanophils are related to gonadal activity. 7. Acidophils present in the rostral pars distalis and pars intermedia do not appear to be related to gonadal activity in C. mrigala. 8. The average weight of the gland is directly related to the state of maturation of the gonads, an observation being recorded here for the first time.     

The cranial nerves of the teleost Trichiurus lepturus

The cranial nerves of the cutlassfish, Trichiurus lepturus, were described from their external brain origin to their most distal points. The nervus olfactorius, nervus opticus, nervus oculomotorius, nervus trochlearis, nervus abducens, nervus glossopharyngeus, and nervus vagus of Trichiurus are characteristic of teleosts. The cephalic autonomic nervous system also follows the general scheme for teleosts. Atypical patterns are exhibited by portions of the ramus mandibularis facialis, ramus mandibularis trigemini, nervus stato-acusticus, and nervus lineae later-alis. A cutaneous ramus mandibularis externus facialis arises from the ramus mandibularis; this cutaneous nerve has been recorded specifically in only certain siluroid catfish. A connection from the ramus mandibularis trigemini to the cutaneous ramus mandibularis externus facialis is present; an equivalent of this connection has been reported only in the silversides, Menidia, and the siluroid catfish Parasilurus. This nerve pattern probably represents an archaic arrangement. The nervus stato-acusticus of Trichiurus is typical for teleosts, except for a branch extending from the posterior part of the nerve; this branch sends connections to the nervus lineae lateralis and then exits the cranium via the vagus foramen. Connections between the nervus lineae lateralis and the nervus stato-acusticus have previously been reported in only the hatchetfish, Argyropelecus, and the bristle-mouth, Cyclothone. This condition may represent a specialized adaptation of certain mesopelagic teleosts having extreme vertical-migration capabilities.