Growth phases of cultured algae used as larval food

A study was undertaken to determine the onset and duration of the growth phases of cultured algae commonly used as larval food (Skeletonema costatum, Chaetoceros calcitrans, Tetraselmis chuii, Chlorella vulgaris, Isochrysis galbana) so as to predict the time of harvest at the desired stage to suit various needs and purposes.

Feeding behavior and food preference of Penaeus monodon Fabricius with scrap tilapia

The time of day during which P. monodon feeds at different depth levels in earthen ponds, and its preference for three types of tilapia feeds (dry, fresh and fermented) were determined. It was observed that P. monodon concentrated at the bottom beds during the day and along the periphery of dikes during night-time, with a slight tendency to swim and feed towards the surface as darkness increased. P. monodon showed special preference for dried tilapia compared to fresh and fermented tilapia. P. monodon also showed adaptability to the platform method of feeding, especially during night-time.

Viability of frozen algae used as food for larval penaeids

Freezing with added chemicals as flocculants and protectants was assessed as a means of preserving stock cultures of 4 algal species used for larval penaeid food Chaetoceros calcitrans, Skeletonema costatum, Tetraselmis chuii and Isochrysis galbana. The maximum storage effectability of the preservation techniques for each species was also determined.

Effect of salinity and food ration level on the growth of Nile tilapia (Oreochromis niloticus L.)

The effect of salinity (0, 10 & 20‰, water temperature 28 ± 1°C) and food ration (3 and 4.5% bw/day) on food consumption and growth of Nile tilapia, Oreochromis niloticus (10.77 ± 0.21g) were investigated. Individual food consumption was measured using X-radiography technique. Salinities (0, 10 & 20‰) did not have significant effect on the growth rate of groups of Nile tilapia fed at different ration levels (3 & 4.5% bw/day). This study showed that the growth of all-male fish was significantly better than all-female fish for all three salinities and two rations. Salinities from 0 to 20‰ had no effect on growth performance of males or female fish. In the present study, it was evident that fish fed at 3% bw/day ration ate all the food offered and fish fed at 4.5% bw/day did not consumed all amounts. Also, growth performance did not significantly differ among fish fed at 3% bw/day ration level and reared at different salinities. Fish reared under higher salinities (20‰) and fed at higher ration (4.5% bw/day) level had skin lesions and injuries on their body. It was assumed that fish fed at higher ration under higher salinities (20‰) and maintained higher osmoregulatory costs together with osmotic stress may have a negative influence on the appetite of fish. Another possibility that may have affected the appetite could be the unionized ammonia levels that were high. The high-unionized ammonia levels combined with the osmotic stress may have been the cause, or have aided, development of skin lesions and injuries on the fish at higher salinities.

Effect of two green algae species (Chlorella sp. & Scenedesmus obliquus) enriched with B group vitamins on food chain of Rutilus frisii kutum (Kamensky, 1901) fry

The Effect of two freshwater green algae species Chlorella sp. & Scenedesmus obliquus enriched (from the beginning of culture and after 96 hours) with different dosages of B group vitamins (0, 0.5, 1, and 2 ml of enriching solution per each liter of algae medium) on fecundity of Daphnia magna and growth of Rutilus frisii kutum fry were investigated in a research from spring, 2008 to autumn, 2009. First, each of the green algae species were cultured purely and massively in the Zander (Z-8+N) medium and then the nutritional value (the amount of protein, lipid, and carbohydrate) of enriched algae were meausered. In this study, enriching of Chlorella sp. & S. obliquus with a suitable mix of B group vitamins significantly improved their nutritive value. So the highest amount of nutritional value of Chlorella sp. was obtained because of enriching with dosage 0.5 ml.l-1 (366.654Kcal) and for Scenedesmus obliquus with dosage of 1 ml.l-1 (376.95Kcal). The acquired amount from control group showed an increase of respectively 42% and 11%. According to the results, increased dosages of enriching solution caused Daphnia fecundity to increase (at both stages : enrichment from the beginning of culture and after 96 hours). So the highest average of D. magna reproduction rate was obtained through being fed with Chlorella sp. and S. obliquus enriched with dosage of 2 ml enriching solution per liter of algae medium. The average fecundity of D. magna fed with Chlorella sp. enriched with dosage of 2 ml.l-1 enriching solution from the beginning of culture and after 96 hours was obtained respectively 2.128 ± 0.375 and 2.1 ± 0.69 and the average fecundity of D. magna fed with S. obliquus enriched with dosage of 2 ml enriching solution from the beginning of culture and after 96 hours was obtained respectively 2.128 ± 0.375 and 2.1 ± 0.69 which showed respectively an increase of 61 ٪, 91٪, 77 ٪, and 83٪ in proportion to the acquired amount from control group. When enriching solution was added to either algae culture medium from the beginning of culture, showed statistically significant differences (P<0.05) between dosages of 0 and 2 ml.l-1, 1 and 2 ml.l-1, and 0.5 and 2 ml enriching solution per each liter of Chlorella sp. culture medium and between dosages of 0 and 1 ml.l-1, and 0 and 2 ml enriching solution per each liter of S. obliquus culture medium. The highest average of body weight gain percentage and specific growth rate of kutum fry was obtained respectively 21.19%, 26.63%, 1.92, and 2.34 from the beginning of culture and after 96 hours with dosage of 1 ml B group vitamins per each liter of Chlorella sp. culture medium, which showed respectively an increase of 50%, 70%, 46%, and 62% in proportion to the acquired amount from control group. In the cases which Chlorella sp. were grown in the medium containing vitamin, from point of view of the average percentage of weight and specific growth rate of kutum fry significant differences were observed on the basis of the result of One-way ANOVA between dosages of 0 and 1, 1 and 2 , 0.5 and 1 ml B group vitamins per each liter. The highest average of body weight gain percentage and specific growth rate of kutum fry was obtained respectively 32.02%, 29.42%, 2.78, and 2.34 from the beginning of culture and after 96 hours with dosage of 2 ml B group vitamins per each liter of S. obliquus culture medium, which showed respectively an increase of 32%, 19%, 28%, and 17% in proportion to the acquired amount from control group. In the cases which S. obliquus were grown in the medium containing vitamin, from point of view of the average percentage of weight and specific growth rate of kutum fry significant differences were observed on the basis of the result of One-way ANOVA between dosages of 0 and 1, 0 and 2. According to the results of the present research we can say that considerable enhancement in the quality of the food of D. magna can be made by manipulation of the nutritional value of fresh water unicellular green algae with suitable mixture of B group vitamins, so that both the fecundity of D. magna will increase and the nutritional requirements of the kutum fry will be filled in this way.

Food preference in the cultured species, Penaeus monodon Fabricius (Crustacea: Decapoda)

The study of food preference is necessitated by the need to promote coastal culture of shrimps in Pakistan. The cultured Penaeus monodon was selected for study. Food preferences have been examined through the analysis of the gut contents. The shrimp shows a seasonal variation in its preference to food and feeding.

Mercury bioaccumulation in pike (Esox lucius) food chain from Anzali Lagoon, Iran

A number of wide-ranging monitoring studies have been performed in order to estimate the degree of mercury (Hg) contamination in freshwater ecosystems. Knowledge regarding contamination of different levels of the food chain is necessary for estimation of total pollutant input fluxes and subsequent partitioning among different phases in the aquatic system. The growing international concern about this environmental data is closely related to the strongly developing ecological risk assessment activities. In addition,freshwater monitoring outputs hold a key position in the estimation of the Hg dose consumed by the human population as it is highly dependent on fish consumption. So monitoring of Hg in the tissue of edible fish is extremely important because of contaminated fish has caused serious neurological damage to new born babies and adults. Mercury tends to accumulate in fish tissue, particularly, in the form of methyl mercury, which is about 10 times more toxic than inorganic mercury. The Anzali lagoon is one of the biggest wetland of Guilan province, which joins to the Caspian sea. Many Chemical and industrial factories plus agricultural runoffs and urban and rural sewages are major polluting sources of the Anzali wetland. Since many of those polluting sources drain their wastes directly or indirectly into the Anzali wetland and their sewages may be polluted with Hg, this study was conducted to find out the bioaccumulation of Hg bioaccumulation in pike (Esox lucius) food chain from Anzali lagoon, Iran. Sampling were carried out from July 2004 to July 2005, in addition 318 speciments of 9 fish species were collected. T-Hg was measured by LECO AMA 254 Advanced Mercury Analyzer (USA) according to ASTM standard No D-6722. Each sample was analyzed 3 times. Accuracy of T-Hg analysis was checked by running three samples of Standard Reference Materials; SRM 1633b, SRM 2711 & Sra 2709. Detection limit was 0.001 mg/kg in dry weight. The Accuracy degree of analyzor equipment with RSD<%0.05 (N=7) was between %95.5 and %105. In overal eigth fish species were distingushed in the gut content of 87 speciments of pike with age 1-5 year and maximum length 550mm. The max. and min. concentration of T-Hg in dorsal muscle of pjke was 0.2ppm in one year and 1.2ppm in five year class. The mean of T-Hg significantly increased with age and length increased (P<0.05).Mercury accumulation pattern in pike was as well as muscle > liver > spleen (P<0.05). THg content in female was higher than male(P<0.05). In contrast the mean of THg concentration in dorsal muscle of eigth fish species as prey was 0.282, 0.261, 0.328, 0.254, 0.256, 0.286, 0.322 and 0.241 ppm for Carassius auratus gibelio, Hemiculter leucisculus, Blicca bjoerkna transcaucasica, Chalcalburnus mossulensis, Rhodeus sericeus amarus, Gambusia holbrooki, Alburnus charusini hohenackeri & Scardinius Erythrophthalmus respectively.Liner regresion indicated that high degree of relationship between age of pike and Uptak/Intake ratio (R2=%99.12) and indicated that the mercury bioaccumulation in the pike dorsal muscle increased with age increased. BFA was >1 and and indicating the mercury biomagnification in the pike food chain. Trophy level of pike in the Anzali lagoon was estimated as well as 3.5 and 4 . It is generally agreed that Hg concentration in carnivorous fish are higher than in noncarnivorous species.

Relative condition factor and food and feeding habits of two ariid catfish from Mumbai waters

Condition factor based on length-weight relationship and food and feeding habits of Arius dussumieri (Black lip sea catfish) and Osteogeneiosus militaris (Soldier catfish) from the Mumbai coast have been studied. Relative Condition Factor showed variations on a monthly basis, and appear to be influenced by feeding and breeding activities. Both the species studied are carnivorous bottom feeders, with crustaceans followed by other smaller fishes forming the major food item in the gut contents.

New food processing equipment

The article presents new food processing equipment for coating and frying. These are predusters, liquid enrobers and applicators for large-particle crumbs.

Survey of food supplementary (Pseudomonas fluorescence) and live food (Algae and brine shrimp) on Penaeus indicus larval stages

In this study ,the effects of Pseudomonas fluorescence obtained from generator pond water of Kolahi as supplementary and four algae consisting of : Chaetoceros sp, Chlorella and Skeletonema sp and Tetraselmis sp, three types of artemia as live food larval states from zoa to postlarvae (PL4 ) Penaeus indicus were investigated. The results indicate that Pseudomonas fluorescence has positive effect on Penaeus indicits larvae growth and their living food. Effective ranges at minimum and maximum were estimated. In most cases optimum dosage was approximately determined. Optimum dosage is between 50 -150 milligrams per liter for living food and Penaeus larval More than 200 milligram per liter resulted in a negative effect on the growth and survival. Also the results indicate Uromiana artemia. Requires a higher concentration of the bacteria the imported artemia. As a conclusion it is recommended to introduce Pseudonionas fluorescence as a new medium for the growth of some mentioned algae .

Live food: a lesser known essential

This article is a short discussion of the requirements for live food production in aquaculture and a brief presentation of the processes involved.