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Open Access
Effect of eyestalk ablation on androgenic gland and male secondary sexual characters in Macrobrachium Idella (Hilgendorf)
(Department of Aquaculture, College of Fisheries,Panangad, 1998) Sherine Sonia, Cubelio; KAU; Thampy, D M
The present study in the prawn, Macrobrachium idella was taken up to find out morphotypic variation among the males, the endocrine basis for these variations and also to know the role if any, the eyestalk endocrines have, on the control of androgenic gland, which in turn is controlling the development of male primary and secondary sex characters. The study conducted to find the relationship between development of sex characters with that of androgenic gland conducted using 30 male prawns of different sizes has ShO\\-l1 that these sex characters are under the control of androgenic gland and have no relationship with that of the body size. Of the 30, 22 individuals were found to have a bodylength to cheliped length ratio below 1: 1.5, their androgenic gland and appendix masculina, not fully developed indicating that they are reproductively inactive. Remaining 8 individuals have a body length to cheliped length ratio above I: 1.5. They have well developed androgenic gland and appendix masculina showing that there is positive correlation between the biomass of androgenic gland and the cheliped length. An experiment conducted to find out the effect of unilateral eyestalk ablation on growth and development of primary and seconadry sexual characters as well as on the androgenic gland, had shown that destalking brings about a positive change in the development of androgenic gland and sex characters. The increase in the size of the androgenic gland and consequent hypertrophy of primary and secondary sexual characters brought about as a result of unilateral eyestalk ablation do indicate that the GlH, a hormone produced in the eyestalk has got an inhibitory effect on androgenic gland as well as on the growth of the prawn, which when removed by " destalking" , results in the enlargement of the androgenic gland and other sexual characters.
Open Access
Effect of eyestalk ablation on growth and reproduction of macrobrachium equidens (Dana)
(Department of Aquaculture, College of Fisheries, Panangad, 1994) Bijulal, P S; KAU; Thampy, D M
The objective of the present study is to evaluate the effect of eyestalk ablation on survival, growth, food conversion and reproduction of adult Macrobrachiumequidens. In the first experiment conducted for 35 days, unilateral eyestalk ablation, bilateral ablation and control treatments were employed at four level of salinities viz 5, 10, 15 and 20 ppt. Complete mortality in bilateral ablation and survival rates of 40.625 % and 68.75% for unilateral and control treatments were recorded at the end of the experiment, the values ranging significantly. The four salinity levels applied did not significantly affect survival. The difference in growth between ablated and unablatedtreatments was insignificant in terms of percentage gain, specific growth rate and average daily percentage gain in terms of length and weight. Salinity levels also showed insignificant difference in growth. Food conversion rate was significantly better in ablated treatment. The different salinity levels tried showed significant difference with regard to food conversion, being better at 20 ppt. In the second experiment conducted for 60 days on females, eyestalk ablation was found to enhance ovarian. In the second experiment conducted for 60 days on females, eyestalk ablation was found to enhance ovarian development in terms of the number of spawns per female. Fecundity, absolute fecundity, and incubation period were not significantly affected although a marginal increase in absolute fecundity could be observed . In the experiments conducted on males it was found that growth rate and cheliped development were significantly better in ablated ones. The number of spines in the appendix masculine, length and biomass of the androgenic gland and width of vas deference, did not show significant variation, although a marginal increase in the biomass of the androgenic gland and the number of spines in appendix masculine was observed in ablated treatment. The different eyestalk ablation experiments have shown that in females destalking does not stimulate growth but there is better response for reproduction, whereas in males there is better growth and only marginal response to reproduction.
Open Access
Conditions for oxygen-packed transportation of penaeus indicus seed
(Department of Aquaculture, College of Fisheries, Panangad, 1994) Geetha Rani Mani, V; KAU; Jayasree Vadhyar, K
The effect of four levels of packing density, (200PL/1, 300PL/1, 400PL/1 and 500PL/1), three levels of salinity (20ppt, 25ppt and 30ppt) and two levels of temperature (30_+ 1°C and 23 + 2°C) on the oxygen consumption rate of Penaeus indicus post-larvae (PL20) was investigated in a closed type respirometer. The dissolved oxygen in the test chamber decreased with the oxygen consumption of the animals. Oxygen consumption was found to vary with ambient oxygen levels at the different packing densities. Among the three salinities, and two temperatures, the lowest rate of oxygen consumption was recorded at 25ppt and 23 +_ 2°C. The effect of these factors on the duration and survival of transportation of the shrimp seed in specially designed hard plastic containers fitted with facilities for oxygen packing under uniform pressure (0.2 Kg/cm2) showed that oxygen packing in hypothermal conditions could help in increasing duration and survival. Salinity of 20-25ppt was found to give longer duration of survival. With increase in packing density, there was considerable reduction in the duration and survival of transportation of the seed. Cannibalism was observed as the major cause of mortality and it could be reduced by lowering of temperature. 200PL/1 could be transported with 100% survival within 6.5-8.5h at ambient temperature of 30+- 1°C under the afore-mentioned type of oxygen-packing. By lowering the temperature to 23 +-_ 2°C it was possible to safely transport with 100% survival the same numbers for more than 20h. Corresponding duration at 500PL/1 with 100% survival was 1-1.5h at ambient temperature and 4-5h at lowered temperature. To reduce cannibalism at ambient temperatures, hollow plastic translucent habitat material was incorporated into the oxygen-packed jars. This experiment was conducted at 25ppt salinity at different packing densities of 200PL/1, 300PL/1, 400PL/1 and 500PL/1. Relatively longer duration and higher survival was observed only at higher packing densities of 400PL/1 and 500PL/1 with the introduction of the habitat material. Water quality parameters in the experimental jars were analysed initially and finally at 70% survival rate. The reduction in dissolved oxygen levels in the oxygen-packed jars was well above the lethal limits even at the highest packing density of 500PL/1 at 70% survival. The decrease in dissolved oxygen levels and increase in ammonia-N and free carbon dioxide, differed with the duration of packing, temperature and packing density.
Open Access
Integrated culture of fish with micropropagated plants in a recirculatory system
(Department of Aquaculture, College of Fisheries,Panangad, 2012) Navya, R; KAU; Devika Pillai
An experiment was designed to study an integrated recirculatory sytem with micropropagated aquarium plants, fish and indigenous filter materials like coir, vetiver and bamboo as the filter media. The plants selected for the study were Bacopa caroliniana, Anubias minima, Aponogeton ulvaceus, Rotala rotundifolia and Nymphoides cristata. The first part of the work was to standardise the micropropagation techniques for the above said plants. Murashige and Skoog medium (half and full strength) was used as the basal medium for the establishment of cultures. The explants varied from nodal segments, rhizome buds, leaf petioles and lateral buds. Surface sterilization was carried out with a range of sterilants like mercuric chloride solution, ethyl alcohol, sodium hypochlorite solution etc. for varying durations and concentrations depending on the type of explant. Effect of growth regulators on explants were studied using auxin IAA and cytokinins, BA and Kn. A liquid culture media with 1.5mg l-1 BA and 0.1mg l-1 Kn concentrations was the best medium for Bacopa caroliniana. A combination of auxin cytokinin like 1.5 mg l-1 BA and 1.0 mg l-1 IAA in liquid culture was the best medium for Rotala rotundifolia. In Nymphoides cristata, hormone concentration of 1.0 mg l-1 each of BA and IAA in liquid culture gave the best results. In Anubias minima, a full MS solid medium with 6.0 mg l-1 of BA gave better results compared to lower levels of BA. In vitro trials for Aponogeton ulvaceus was not successful due to the exudation of phenolic extracts in all the treatments which eventually lead to the death of the tissues. Hardening success was 90 percent, 100 percent, 70 percent, 100 percent in the case of Anubias minima, Nymphoides cristata, Rotala rotundifolia and Bacopa caroliniana respectively. The micropropagated plants were incorporated in the recirculatory system along with fish and three different biofilter materials like coir, vetiver and bamboo splits. The study focused mainly on the filtering efficiency of the three filters based on the nitrification curves. The plants were included in the system to be a part of biofilter and their exclusive role in nitrification was not studied since this is a preliminary work. A nitification graph was plotted with the observed values of ammonia, nitrite and nitrate in the three different biofilter systems and compared with a control. It was inferred that coir fibres were the best of filter materials tried in nitrification followed by bamboo and vetiver. The control system took more time (45 days) in stabilizing ammonia levels due to lack of a substratum for growing nitrifying bacteria.
Open Access
Evaluation of growth in Penaeus Monodon Fabricius by incorporation of selected nonhormonal growth promoters in the diet
(Department of Aquaculture, College of Fisheries,Panangad, 1997) Vinodh, M P; KAU; Susheela, Jose
The effect of three growth promoters viz. Chitin, chitosan and glucosamine each at three levels (0.25, 0.5 and 1g per 100g diet) were evaluated in P.monodon early juvenile for a period of 70 days. The three growth promoters at three level were tested with 3 replicates for each treatment. The growth promoters were incorporated into a soyflour clam meal based practical diet containing 40% protein and fed to the shrimps adlibitum. The results showed that the overall growth was not affected by dietary inclusion of chitin though the growth rate at 0.25g chitin per 100g diet was comparatively better than that of the control diet. Chitin does not seem to have any effect on specific growth rate of the juveniles although incorporation at 0.25g/100g diet improved the food conversion of the animal significantly over the control. Percentage survival values were also not significant at any level of incorporation. It does not seem to improve protein efficiency ratio and productive protein value too. Incorporation of chitosan at 0.25 and 0.5g/100g diet significantly improved the weight gain, specific growth rate, food conversion ratio, protein efficiency ratio and productive protein value. However inclusion of chitosan at 1g/100g diet did not have any effect on growth though it significantly improved food conversion ratio, protein efficiency ratio and productive protein value. None of these treatments had any effect on survival of the animal. Incorporation of glucosamine into the diet at 0.25g/100g diet was found to be the most efficient amongst the different treatments as evidenced by various growth parameters. It was significantly different from all other treatments in terms of growth, productive protein value and protein efficiency ratio. However it was not significantly different from glucosamine incorporation at 0.5g/100g diet in terms of specific growth rate and food conversion ratio. Enhancement of glucosamine level to 1g/100g diet was found to give poor result compared to the control. The survival rate of shrimps were not significantly different among the treatments. Hence in the present study, glucosamine was found to be superior to chitin and chitosan as a growth promoter and the optimum level was identified as 0.25g/100g diet for P.monodon juveniles
Open Access
Effect of different dietary levels of lecithin on growth,survival,moulting and body phospholipid levels in Macrobachium Rosenbergii postlarvae
(Department of Aquaculture, College of Fisheries, Panangad, 1996) Mahesh, S; KAU; Sebastian, M J
The effect of dietary levels of lecithin on growth, survival moulting, FCR and body phospholipid levels of early postlarval freshwater prawn macrobrachium rosen bergii was examined using semi-purified diets in a 56 day feeding experiment. Five casein-egg albumin based semi-purified diets incorporated with 0,2.5,5,7.5 and 10% of purified soy lecithin (60% phosphatidylcholine) were formulated and fed to prawns (ten numbers per treatment) with an initial mean weight of 0.05386g. In order to examine the influence of lecithin at different growth stages of postlarvae the assessment was made every fourteen days during the study period. The result showed that although the overall growth performance was not affected by dietary inclusion of lecithin, SGR% of the prawns fed with the diet containing 2.5% of lecithin showed a significant difference at P<0.01level during the first fourteen days of growth. Similarly the FCR also showed significant variation (P<0.01) between the diets tested in the first and second fortnights (14th and 28th day). In the first fortnight the diets (D1, D2 and D3) produced consistent FCR, while the diets supplemented with higher levels produced higher values. No significant differences (P<0.01) between treatments were detected with regard to survival rate, moulting frequency and body phospholipid levels of the prawns with the termination of the experiment. The prawns moulted once in every night days and no abnormalitied like exuvia entrapment were noticed in any of the experiment animals . Increment of body phospholipids with respect to levels of dietary lecithin suggests a possible replacement of body PL pool with that of dietary PL. The result of the study suggests that supplementation of lecithin at a level of 2.5% in the diet can accelerate growth and improve FCR during the early postlarval phase of Macrobrachium rosenbergii (ie, upto 4 weeks after larval settlement) beyond this, supplementation of lecithin is not needed in the diet. No other deficiency of excess symptoms was detected in the experimental prawns and it is found that lecithin is not responsible for Exuvia Entrapment Disease in Macrobrachium rosenbergii postlarvae.
Open Access
Effect of different diets on growth and survival of angel fish Pterophyllum scalare (Lichtenstein) fry
(Department of Aquaculture, College of Fisheries, Panangad, 1997) Neelakanteswar, A; KAU; Mathew, P M
The effect of different diets on the growth and survival of Angel fish, Pterophyllum sealare (Lichtenstein) larvae was studied. One day old free swimming hatchlings were used in the study for a period of 30 days. The different diets used were Artemia nauplii, Moina micrura, artificial diet, Artemia nauplii + Moina micrura and Artemia nauplii + artificial diet, with four replicates for each treatment. The experiment was repeated twice in order todetermine the consistency of the result. The results showed that the growth of larvae, in terms of gain in length and weight and specific growth rate, was maximum with the mixed diet of live foods. The differences in growth between artificial diet and mixed diet of Artemia nauplii + artificial diet were not consistent. No significant difference was found in the survival rate of larvae fed different diets. O:N ratios showed that the nutritional state of the larvae fed artificial diet was more or less similar to that fed mixed diet of Artemia nauplii + artificial diet, which in turn was comparable with that fed live foods. Thus, the artificial diet has been found to be an effective replacement diet in the larval rearing of Angel fish.
Open Access
Differential growth in the giant freshwater prawn Macrobrachium rosenbergii (De Man) during nursery rearing phase
(Department of Aquaculture, College of Fisheries, Panangad, 1997) Mainuddin, Ahmed; KAU; Thampy, D M
The present study was conducted on freshwater prawn Macrobrachiumrosenbergii (De Man) to find the effect of stocking density and provision of additional substrates in rearing tanks, on differential growth among different size groups of juveniles during early growth phase. The first experiment conducted with various stocking densities ranging from 25 to 800 nos/m2 had revealed that the differential growth and the average size of the post larvae were inversely proportional to the stocking density; however the total biomass production was directly related to the stocking density. The survival rate was not much affected by variation in the stocking density, being almost uniform (87 – 100%) among various treatments. The second experiment has shown that provision of additional substrates could not help to reduce differential growth, rather it enhanced it. However it helped to enhance the average growth, total biomass production and the survival rate. The size grading of juveniles after an initial nursery rearing period of 35 days, into four groups such as small, medium, large and a recombined control group and growing them separately for another 35 days has revealed that the size grading helped in reducing the differential growth and increasing the total biomass production, but could not help to increase the survival rate. It was found that the total biomass production in large size group was about four times higher than that of the small size group and about two times than that of the control group, indicating that growing M. rosenbergii juveniles in grow out systems after size grading and discarding the smaller size group, will be advantageous for increasing production. The male secondary sex character, the appendix masculine was found to appear after 154 days of metamorphosis, when the prawn had reached a size of 6.2 cm and 1.75 g. An allometric pattern of growth was observed in case of appendix masculine wherein a higher ratio of 1:1.34 was recorded in comparison to 1:1.14 of that of the endopod of the second pleopod, in the subsequent moult.
Open Access
Characterization of different stocks of Macrobrachium rosenbergii and development of genetically improved strain through selective breeding
(Department of Aquaculture, College of Fisheries, Panangad, 2010) Shyla, G; KAU; Mohanakumaran Nair
Giant freshwater prawn Macrobrachium rosenbergii (de Man, 1879) is an important species suitable for culture in inland and low saline coastal water bodies. Information on the genetic structure and variation among cultured species are essential for genetic approaches to optimize conservation strategies and breeding programmes for improving stocks. DNA based markers can be used to assess more precisely the genetic variations in the entire genome. Natural populations of M. rosenbergii inhabiting the rivers in different geographical areas of India show wide variation in morphological traits and economic characters. The present work envisages studying the genetic diversity of wild populations of M. rosenbergii collected from different parts of India through phenotypic characters and molecular marker studies. It also aims to develop a superior strain by combining the desirable characters through selective breeding. In this study genetic characterization of Andhra Pradesh (AP), Orissa (OR) and Kerala (KR) stocks of Macrobrachium rosenbergii were done with RAPD and Microstellite markers. Marker analysis showed variation between stocks and AP showed more genetic distance from OR and KR populations.Moreover KR stock from Achankoil River showed slight similarity with AP. Phenotypic trait analysis was done with three stocks. Egg diameter, larval hatch fecundity, larval rearing period, survival rate and larval length were estimated. Highest egg diameter and hatch fecundity were shown by OR and KR populations. AP showed minimum larval rearing period and maximum survival rate. Maximum larval length was for KR. Stress tolerance studies were conducted in V and X stage of M.rosenbergii larvae with temperature, salinity, formaldehyde and ammonia to estimate the relative differences in the ability of different populations to withstand stressed conditions. Among base population KR population showed highest tolerance towards temperature, salinity, formaldehyde and ammonia.Stage wise tolerance variations also found in all populations. X stage showed more tolerance to all stressors except ammonia. Comparison of other economically important parameters such as disease resistance, quality of flesh, percentage survival, growth rate, percentage morphotypes and head tail ratio were also done. Disease resistance was tested with white tail virus and bacteria (Enterococcus aerogenes) by challenge study. In both studies KR population exhibited better tolerance than other populations. Prophenoloxidase activity and total haemocyte count was also estimated in infected prawns to check the immune response. Here again KR showed higher activity and count. Flesh quality of three populations was estimated by carcass proximate analysis. In this study, no variation in body composition was shown by three stocks. Percentage survival rate and weight gain of three populations in cage were estimated. Maximum survival rate was found in AP and highest growth was found in KR stock. Analysis of percentage morphotypes of various populations showed the maximum OC for AP and SM for OR stock, with no significant variations in percentage BC and female prawns, head tail ratio, which was calculated to find out the yield of meat revealed the least ratio for KR. Large healthy prawns of the three stocks were selected from families showing better performance. Breeding experiment was conducted to produce six crosses viz. Andhra Pradesh (male)×Orissa (female) APOR, Orissa (male) × Andhra Pradesh (female) ORAP, Andhra Pradesh (male) × Kerala (female) APKR, Kerala (male) × Andhra Pradesh (female) KRAP, Orissa (male) × Kerala (female) ORKR, Kerala (male) × Orissa (female) KROR. Different phenotypic characters and economically important traits of F1 generations of hybrids were also studied. KROR showed better egg diameter, hatch fecundity, larval survival rate and larval length. But larval rearing period was minimum for APKR. KROR showed resistance to viral and bacterial diseases, which was similar to that of KR and better than other hybrids. In cage culture APOR showed better survival rate, while growth rate was significantly higher for KROR, which was more than that of base populations. Analysis of percentage morphotypes showed a similar pattern as that of base populations. Lower head -tail weight ratio was shown by KROR, which was lower than that of KR. Estimation and comparison of heritability of weight of three better performing hybrids were done. From the data it was found that maximum heritability of weight was for KROR (.75) followed by APKR (.161) and APKR exhibited no heritability.

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