Volume 56, Issues 1-4, 2004

Alteration Of Renal Tissue In Nile Tilapia, Oreochromis Niloticus, After Transfer To Saline Water

Benli, A.C. Karasu; Yildiz, H. Yavuzcan — Thu, 01 Jan 2004 00:00:00 GMT

Changes in renal tissues and plasma osmolality were investigated in Nile tilapia (Oreochromis niloticus) 72 hours after transfer from fresh water to 9 or 18 ppt salinity. Exposure to high salin- ity was associated with cell infiltration into renal tissue. Plasma osmolality increased with increasing salinity but the hematocrit remained unchanged.

Masculinization Of Genetic Females Of The Common Carp (Cyprinus Carpio L.) By Dietary Administration Of An Aromatase Inhibitor

Tzchori, Itai; Zak, Tatyana; Sachs, Ofer — Thu, 01 Jan 2004 00:00:00 GMT

In the present study, we demonstrated the ability of Fadrozole, an aromatase inhibitor, to induce sex inversion of genetically female common carp fry during the critical sex differentiation period. Thirty-day-old female fingerlings with a mean initial weight of 4.0 g (experiment I) and 3.5 g (experiment II) were fed a diet containing Fadrozole for 36 or 50 days, respectively. Not a single male was found in the control groups of both experiments. In experiment I, Fadrozole at 200 mg/kg feed resulted in 58.6% males, while fish receiving 17α-methyltestosterone at 50 or 100 mg/kg feed resulted in only 5-10% males. In experiment II, the efficiency of Fadrozole was dose- dependent; the lower dose of 100 mg/kg caused masculinization in 86% of the treated fry while the higher doses of 200 and 400 mg/kg feed increased the percentage of males to 97%. These results confirm the importance of aromatization during the labile period in common carp since low aromatase activity during this period, regardless of genotype, resulted in masculinization.

In Vitro Melatonin Rhythm Reveals A Clocked Pineal In The European Sea Bass, Dicentrarchus Labrax

Ron, Benny — Thu, 01 Jan 2004 00:00:00 GMT

The melatonin-generating system of the European sea bass, Dicentrarchus labrax, was studied in vitro using a perfusion tissue culture methodology. The examined properties included photic entrainment in the pineal gland, and circadian rhythmicity in alternating dark and light, in contin- uous darkness, and in continuous light. Pineal glands were removed from adult fish and placed in a perfusion tissue culture at a constant temperature of 24°C. Melatonin discharge into the cul- ture medium was measured using radioimmunoassay. Melatonin concentrations during a pho- toperiod of 12h light:12h dark were low during the light periods and high during the dark. The melatonin discharge was inhibited by continuous light but strong and rhythmic in continuous dark with a circadian period (Tau) of about 24 h (n = 10). The results demonstrate that the European sea bass pineal gland is photosensitive, with ability to be entrained, and contains an internal cir- cadian oscillator that regulates melatonin production.

Effect Of Feeding Frequency On Consumption, Growth, And Efficiency In Juvenile Tilapia (Oreochromis Niloticus)

Thu, 01 Jan 2004 00:00:00 GMT

Triplicate groups of juvenile Oreochromis niloticus (34.4 g) were fed a commercial diet once, twice, three, or five times a day for 29 days. Consumption, growth, and feed utilization were eval- uated. No significant differences in growth, feed efficiency, or protein utilization were detected among the fish fed two, three, or five times daily, but all were significantly better than in fish fed only once. Fish fed three meals had significantly higher gross energy and lipid and lower crude protein contents than fish in the other treatments (p<0.05). Energy retention in fish fed three times daily (84.7%) was significantly higher than in fish fed five times (49.4%). Feeding juvenile tilapia nutrient dense pelleted feeds obviates the need for frequent feedings.

Effect Of Feed Type On Growth And Fertility In Ornamental Fish, Xiphophorus Helleri

James, Raja; Sampath, Kunchitham — Thu, 01 Jan 2004 00:00:00 GMT

The effects of feed type on feed intake and conversion, ovary weight, and fertility were studied in red swordtail, Xiphophorus helleri, for 235 days. Five groups of 30-day-old juveniles (0.05±0.001g; 16.84±1.59 mm) were fed Artemia, earthworms, liver, pelleted feed, or a mixed diet. Mean body length and weight were higher in fish that consumed the mixed diet or Artemia than in those that consumed the other diets. Pelleted feed produced the highest feeding rate but the poorest conversion rate. Fish fed pelleted feed consumed 143 mg/g/day, which was con- verted into 13 mg/g/day flesh. Those fed the Artemia, earthworm, liver, or mixed diets consumed 46, 56, 89, and 84 mg/g/day, repectively, which were converted into 16, 18, 21, and 24 mg/g/day, respectively. The conversion rate dropped after parturition, possibly due to allocation of a major portion of the feed energy to development of gonads and young. Irrespective of feed type, gonads appeared on day 42. On day 84, the gonad weight of fish fed earthworms was 16 mg (wet weight), significantly (p<0.01) increasing to 25 mg in fish fed Artemia, 31 mg in fish fed liver, 86 mg for pellets, and 145 mg for the mixed diet. A similar trend was noted in the gonadosomatic index. Females fed the mixed diet, Artemia, and liver released 753, 612, and 509 fry in four breeding cycles while those fed earthworms and pellets bred only three times, releasing 315 and 155 fry, respectively.

Use Of Nitrification Inhibitors To Increase Efficiency Of Nitrogenous Fertilizers In Aquaculture

Thakur, Amrita; Banerjee, Abira; Chattopadhyay, G.N. — Thu, 01 Jan 2004 00:00:00 GMT

High doses of nitrogenous fertilizers are often applied in fishponds but only a small part of the added nitrogen is utilized for improving primary productivity and, thereby, fish yields. A large por- tion of the nitrogen is lost from the pond environment through various mechanisms, especially nitrification. In the present investigation, we studied the effects of three nitrification inhibitors: (a) neem (Azadirachta indica) extract, (b) karanj (Pongamia glabra) extract, and (c) sodium azide (NaN3), on the transformation of applied nitrogen in simulated fishpond conditions. The study revealed that nitrification inhibitors considerably retard the rate of nitrification from the ammoni- um form of nitrogen (NH4+), resulting in a higher amount of nitrogen in the soil and water. The increased nitrogen concentration significantly increased gross primary production and, hence, improved the efficiency of the added nitrogen.

Correlation Between Biochemical And Spermatological Parameters In Rainbow Trout (Oncorhynchus Mykiss) Semen

Secer, Selçuk; Tekin, Necmettin; Bozkurt, Yusuf; Bukan, Neslihan; Akcay, Ergun — Thu, 01 Jan 2004 00:00:00 GMT

Levels of biochemical parameters in seminal plasma and physical parameters of rainbow trout (Oncorhynchus mykiss) semen were determined and compared. Seminal plasma contained 80.51±31.48 mmol/l Na+, 46.21±12.58 mmol/l K+, 4.65±1.57 mg/dl Ca2+, 3.48±1.18 mEq/l Mg2+, 112.5±25.93 mmol/l Cl-, 1.33±0.76 mg/dl glucose, 0.15±0.09 g/dl protein, 2.55±2.47 mg/dl cho- lesterol, 8.0±2.84 mg/dl triglyceride, and 31.65±40.78 mg/dl urea. Semen volume was 19.9±21.43 ml, spermatozoa motility 60.0±30.09%, duration of spermatozoa movement 174.0±1.82 s, spermatozoa concentration 1.52±0.70 x 109/ml, total spermatozoa number 44.25±64.59 x 109, and pH 6.7±0.25. There were significant positive correlations between semen volume and Na+ (r = 0.667, p<0.05), total spermatozoa number and semen volume (r = 0.977, p<0.01), total spermatozoa number and spermatozoa concentration (r = 0.652, p<0.05), Na+ and Cl- (r = 0.733, p<0.05), Na+ and triglyceride (r = 0.632, p<0.05), K+ and protein (r = 0.728, p<0.05), and Ca2+ and protein (r = 0.685, p<0.05). Significant negative correlations were found between Cl- and glucose (r = - 1.00, p<0.05), and triglyceride and urea (r = -0.716, p<0.05). Consequently, although there were no definite correlations between biochemical and spermatological parameters, it was observed that a higher Na+ content has a positive effect on semen volume.

Digestibility Of Nutrients And Energy In Diets For The African Catfish Clarias Gariepinus (Burchell 1822)

Pantazis, Panagiotis A.; Neofitou, Christis N. — Thu, 01 Jan 2004 00:00:00 GMT

A purified diet, the raw material zein, and two diets composed of complex foodstuffs (fishmeal, soy, wheat) were tested for eight months in the African catfish Clarias gariepinus (Burchell 1822) to determine the in vivo Apparent Digestibility Coefficients (ADC) for dry matter, crude protein, lipid, carbohydrates, ash, energy, and amino acids. Feces were collected by sedimentation and digestibility coefficients were calculated using chromium oxide as an external indicator. Average ADCs ranged 54-96%. The ADC of crude protein (80-90%) was similar to previously recorded ADCs. Ash digestibility (54-89%) varied significantly between diets, probably as the result of the reduced bioavailability of minerals and trace elements in the constituent raw materials. ADC for individual amino acids ranged 82-99%. Zein, as an experimental feed ingredient, had an accept- able ADC for both gross nutrients and amino acids. When the nutrient level in the test ingredi- ent differed greatly from that in the reference diet, calculation of ADC was based on relative nutri- ent contributions. Results are discussed in relation to the nature of the dietary ingredients and their suitability for related experimental nutritional work.

Effects Of Fish Density On Spread Of Infectious Hematopoietic Necrosis Virus (IHNV) In Rainbow Trout, Oncorhynchus Mykiss

Ogut, H.; Reno, P.W. — Thu, 01 Jan 2004 00:00:00 GMT

Rainbow trout (Oncorhynchus mykiss) were held at one of seven densities (8, 4, 0.63, 0.31, 0.16, 0.08 or 0.012 fish per liter) and challenged to the infectious hematopoietic necrosis virus (IHNV) by cohabitation with a single presumably infected donor fish. The trout were exposed to the IHNV-infected fish for 11 days to determine the effect of density on occurrence, spread and prevalence of the disease. The host density and IHNV prevalence were positively associated (r2 = 0.89, regression analysis) with no occurrence of the virus at the two lowest densities (0.08 and 0.012 fish/l). Host density, therefore, is a key factor in determining the incidence and magnitude of IHNV infection.

Successful Replacement Of Fishmeal By Plant Proteins In Diets For The Gilthead Seabream, Sparus Aurata L.

Kissil, George Wm.; Lupatsch, Ingrid — Thu, 01 Jan 2004 00:00:00 GMT

Soy protein concentrate, wheat gluten, and corn gluten meal were evaluated in combination and as sole dietary protein sources in diets for gilthead seabream. A growth trial and digestibility determinations demonstrated the effectiveness of these plant proteins as alternatives to fish- meal. Digestibility trials indicated superior protein digestibility for soy protein (92%), wheat gluten (96%), and corn gluten (90%) in comparison with fishmeal (86%), while energy digestibility was higher than fishmeal (84%) only in wheat gluten (91%; it was 75% for soy protein and 72% for corn gluten). For the growth trial, eight isonitrogenous and isoenergetic (as-fed basis) diets were formulated with differences in the protein sources. Growth in the range of 40-130 g was superi- or to the fishmeal control with the diet containing wheat gluten but inferior in the diets containing soy protein concentrate or corn gluten meal. Diets that replaced 25-100% of the fishmeal with a mixture containing equal portions of all three plant proteins outperformed the control with a 9- 16% greater weight gain and 4-10% lower feed conversion ratio. The use of soy protein or corn gluten as the sole protein source in diets for seabream is not recommended but their use in com- bination with wheat gluten can provide a partial or complete alternative to fishmeal. However, the cost of supplemental arginine made replacement economic at only the lowest replacement level (25%). An in-depth evaluation of the need for this amino acid in the protein mixture could signif- icantly affect the feasibility of using higher replacement levels.

Enteric Red Mouth Disease In Cultured Rainbow Trout (Oncorhynchus Mykiss) On The Black Sea Coast Of Turkey

Karatas, Süheyla; Candan, Akin; Demircan, Didem — Thu, 01 Jan 2004 00:00:00 GMT

Although Yersinia ruckeri, the etiological agent of the enteric red mouth disease (ERM), has been isolated from freshwater fish in several countries, there are few reports of its presence in cultured sea and brackish water fish. The aim of this study was to isolate and identify the etio- logical agent of disease outbreaks that occurred in rainbow trout cage farms on the Black Sea coast of Turkey in 2002. Clinical observation, biochemical, API 20 NE, and agglutination tests allowed the diagnosis of ERM caused by Y. ruckeri, which was successfully treated with med- icated feed (oxytetracycline at 75 mg per kg body weight per day for 10 days).

Dietary Histidine Requirement Of Fingerling Indian Major Carp, Labeo Rohita (Hamilton)

Abidi, Shabihul Fatma; Khan, Mukhtar A. — Thu, 01 Jan 2004 00:00:00 GMT

A 6-week growth trial was conducted to assess the dietary histidine requirement of fingerling Indian major carp, Labeo rohita (3.50±0.04 cm; 0.40±0.02 g) by using amino acid test diets (40% crude protein; 4.28 kcal/g) containing casein, gelatin, and L-crystalline amino acids. Diets with graded levels of histidine (0.25, 0.50, 0.75, 1.00, 1.25, and 1.50% of the diet) were fed to tripli- cate groups of fingerlings at 5% of their body weight divided into two feedings (07:00 and 17:30). Live weight gain, specific growth rate, protein efficiency ratio, and feed conversion ratio were sig- nificantly (p<0.05) affected by dietary histidine concentration. Weight gain and conversion effi- ciencies were best at 0.75% dietary histidine. Whole body protein content was highest and mois- ture and fat were lowest in the 0.75% dietary histidine treatment while whole body ash was the same at all treatment levels. Second-degree polynomial regression analysis of the live weight gain and feed conversion ratio resulted in more accurate histidine requirement estimates of 0.90 and 0.82% of the dry diet, respectively, corresponding to 2.25 and 2.05% of the dietary protein. It is recommended that dietary histidine be included at a level of 0.82% of the feed, correspond- ing to 2.05% of the dietary protein, for optimal growth in L. rohita fingerlings.

Spawning And Larvae Production Of Common Pandora, Pagellus Erythrinus L.

Güner, Yusuf; Özden, Osman; Altunok, Muhammet; Koru, Ediz; Kızak, Volkan — Thu, 01 Jan 2004 00:00:00 GMT

Spawning of the common pandora (Pagellus erythrinus L.) in captivity was studied at ambient temperature (21.2±1.2°C) during the breeding season in 1998. Broodstock were cultivated in net fishpens and spawned in large fiberglass tanks (10 m diameter) between June and July. Approximately 33.2 million eggs were collected from 30 mature 4-7 year old females, 97% of which were buoyant healthy eggs with diameters ranging 753-801 μm. The eggs were incubat- ed at 19, 21, or 23°C and development and morphological changes were observed until day 50. The best hatching rate (88.9%) was obtained at 19°C. Swim bladder inflation occurred 8-20 days after hatching. The average survival at day 50, at an initial density of 40 larvae/l, was 3.2%. Exogenous feeding began on day 3. Larvae were first fed rotifers, Brachionus plicatilis, and later Artemia nauplii. Larvae completed yolk absorption 78 hours after hatching. A green water envi- ronment was maintained by introducing cultured microalgae (Nannochloropsis oculata and Tetraselmis suecica). Larvae (13.3 mm) transformed into juveniles (18.71 mm) 29-37 days after hatching.

Effects Of Alum On The Quality Of Aquaculture Effluents In Settling Ponds

Rowan, Martha; Gross, Amit; Boyd, Claude E. — Thu, 01 Jan 2004 00:00:00 GMT

The effectiveness of alum (aluminum sulfate) in reducing the concentrations of potential pollu- tants in pond effluents was investigated in catfish production ponds. Application of alum at 50 mg/l to water remaining in ponds immediately after seining for harvest did not generally result in significantly greater removal of nutrients and solids than did settling alone, although removal rates of some variables were initially higher in the alum treated ponds. Within four hours of sein- ing in both alum treated and untreated ponds, there was removal of more than 85% of total sus- pended solids, 75% of total phosphorus, 72% of turbidity, and more than 40% of biochemical oxygen demand and chemical oxygen demand. Concentrations of soluble reactive phosphorus decreased after 48 h, but total ammonia nitrogen was not removed. Alum may be more effective in improving water quality in settling ponds if it is applied after the initial sedimentation has occurred.

Fertility Problems In The Second Generation Of A Four-Species Tilapia Cross

Hulata, Gideon; Cnaani, Avner; Slossman, Tatiana; Gall, Graham A.E. — Thu, 01 Jan 2004 00:00:00 GMT

Reproductive problems were encountered in attempting to produce the second generation of a four-way cross of tilapia from interspecific F1 hybrids. The cross (Oreochromis mossambicus x O. aureus) x (Sarotherodon galilaeus x O. niloticus) successfully bred for one generation, how- ever, not even a single batch of progeny was obtained in the subsequent generation. It was con- cluded that the complex genetic structure of this cross caused the fertility problem. Any similar breeding programs that are based on multi-species crosses should take into consideration that reproductive problems may occur.

A Preliminary Study On The Effects Of Salinity On Egg Development Of European Squid (Loligo Vulgaris Lamarck, 1798)

Sen, Halil — Thu, 01 Jan 2004 00:00:00 GMT

The effects of salinity on the development and incubation of European squid (Loligo vulgaris, Lamarck, 1798) eggs were investigated from December 2001 to March 2002. The egg capsules were incubated in 37‰, 34‰, 31‰, 28‰, and 0‰ salinity without any acclimation process. Mean temperature was 12±2.0°C. Illumination was maintained at 1.5 lux at the water surface. Full embryonic development and hatching were observed after 64-76 and 66-76 days at 37‰ and 34‰ salinity, respectively. Hatching rates were estimated as 88.5% at 37‰ and 60% at 34‰. In salinity below 34‰, the eggs died at very early stages. Average dorsal mantle lengths of the new hatchlings were 2.53±0.08 mm at 37‰ and 2.48±0.11 mm at 34‰.

Amino Acid Profiles In The Midgut, Ovary, Developing Eggs And Zoes Of The Mud Crab, Scylla Serrata

Peñaflorida, Veronica Dy — Thu, 01 Jan 2004 00:00:00 GMT

Culture of the mud crab, Scylla serrata, is beset by low and inconsistent survival of larvae in spite of the high fecundity of crab breeders. The nutrition of the embryo and pre-feeding zoea depends on what is stored in the egg. The protein and free amino acid contents of the midgut gland, ovary, eggs, pre-feeding zoea, live food and a maintenance diet for broodstock were analyzed by HPLC. The maintenance diet had lower arginine, histidine, methionine, threonine and tryptophan than the ovary and egg. The midgut had higher phenylalanine and valine and lower leucine, methionine and tryptophan than the ovary. Amino acid profiles in the ovary, egg and zoea showed that methionine was highest in the ovary and leucine was highest in the zoea. Low val- ues were observed for isoleucine and valine in ovary, arginine in egg, methionine and pheny- lalanine in zoea. When live foods were compared to zoea, histidine in Brachionus, leucine and tryptophan in Artemia, and arginine, leucine and valine in Acartia were low. Essential free amino acids in fertilized eggs were 2.5 times higher than in unfertilized eggs. Arginine, histidine, lysine, methionine, tyrosine and threonine decreased with egg embryogenesis, suggesting that these are the major free amino acids utilized as the egg develops. Information on egg and zoea amino acids can be used to predict viable crab eggs while information on amino acid profiles in the ovary, egg and zoea can be used to develop broodstock diets. Identification of limiting amino acids in live foods can be used to develop larvae diets.

Reproductive Biology Of The Shi Drum (Umbrina Cirrosa) In Captivity And Induction Of Spawning Using Gnrha

Thu, 01 Jan 2004 00:00:00 GMT

The reproductive biology of the shi drum (Umbrina cirrosa) in culture was histologically exam- ined and sperm quality was monitored during an entire reproductive period. Already in April, the ovary contained oocytes in all stages of maturation, from primary oocytes to full vitellogenesis, as expected from a group-synchronous multiple-batch spawning fish. Vitellogenesis of the first batch of oocytes occurred very rapidly and their mean diameter (500 μm) did not increase sig- nificantly (p>0.05) as the reproductive period proceeded. The spermiation index peaked in May- June, but fish never produced copious amounts of milt upon abdominal pressure. The sperma- tozoa motility percentage remained unchanged throughout the spawning season (80%) and a significant percentage (40%) maintained viability after overnight storage at 4°C. Sperm density and motility duration increased during the reproductive period and varied 13-26 x109 spermato- zoa/ml and 26-40 s, respectively. Spontaneous spawning was not observed during the two-year study. Injection of post-vitellogenic females with an agonist of gonadotropin-releasing hormone (GnRHa) was successful in inducing a single spawning after two days, with fertilization, hatch- ing and 4-day larval survival rates of 65%, 42-76% and 46-80%, respectively. The results under- line the failure of female shi drum in culture to undergo final oocyte maturation and, although GnRHa injection was effective in inducing spawning of viable eggs, multiple treatments did not induce multiple spawns, as was expected from fish with multiple-batch group-synchronous ovar- ian biology.

Effects Of Feeding Frequency On Growth And Fecundity In An Ornamental Fish, Betta Splendens (Regan)

Thu, 01 Jan 2004 00:00:00 GMT

Experiments were performed to investigate the influence of feeding frequency on growth, gonad weight and fecundity in an ornamental fish, Betta splendens. Five groups of 30-day-old juveniles (0.045±0.01 g; 14.43±2.2 mm) were fed either one meal in three days, one meal in two days, one meal per day, two meals per day or three meals per day for 77 days. Mean body length and weight increased linearly in all groups. However, the feeding, growth and fecundity rates increased with feeding frequency up to two meals a day, thereafter they declined. Fish fed once in three days consumed only 266 mg feed (dry weight) that was converted into 61 mg flesh (dry weight). Fish fed once in two days consumed 384 mg and gained 116 mg flesh. For fish fed once a day, 543 mg were consumed and converted to 175 mg flesh. For those fed twice a day, 1000 mg feed produced 279 mg flesh and for those fed three times a day, 886 mg food produced 242 mg flesh. The growth rate was significantly and drastically lower in all groups after spawning began, perhaps due to diversion of assimilated food energy for egg production. The gonad developed significantly (p<0.05) earlier in fish given at least one meal per day and weighed 85.5, 158 and 246.5 mg (wet weight) in fish fed once, twice and three times per day, respectively, on day 35 while it weighed only 56 and 93.5 mg on day 63 in fish fed once in three or two days, respectively. A similar trend was noted in the gonadosomatic index. Female B. splendens laid 274 and 454 eggs in groups fed once in three or two days, and 1833, 2202 and 632 eggs in groups fed once, twice or three times a day, respectively. Feeding three times a day resulted in total mortality of the spawners during the third spawn. Two meals a day elicited the maximum growth and reproductive performance and hence is considered optimal for B. splendens.

Economic Evaluation Of Multiple Research Innovations On An Eel Farm

Din, Gregory Yom; Zugman, Zinaida; Degani, Gad — Thu, 01 Jan 2004 00:00:00 GMT

An approach for evaluating multiple innovations of an aquaculture farm is proposed, based on a model of induced innovations, supplemented with a bio-economic table for the calculation of pro- duction function. Data gathered from a model eel farm were used as an example. The proposed approach enables evaluating each innovation to determine which is the most profitable.