Now showing items 1-5 of 5

    • Article

      Changes in plasma osmolality and chloride concentration during abrupt transfer of milkfish (Chanos chanos) from seawater to different test salinities 

      RP Ferraris, JM Almendras & AP Jazul - Aquaculture, 1988 - Elsevier
      Milkfish juveniles (40, 120 or 260 g) were acclimated to 32 ppt seawater, then abruptly transferred to water with salinities of 0, 16, 32 (control) or 48 ppt. Blood samples were taken 0, 1, 2, 3, 5, 7 or 14 days after transfer. Survival rate was 95% or greater in all salinities. Plasma osmolality in fish exposed to salinities other than 16 or 32 ppt deviated from control values immediately after transfer but were subsequently regulated to near normal levels after several days. Although these deviations were significant, they were relatively small (≤20% of initial) as plasma osmolality changed by less than 0.07 mOsm/kg per unit change environmental salinity. Plasma chloride values generally followed the same pattern of changes as plasma osmolality. When these deviations were integrated across time, summed deviations (mOsm·day kg−1 or mEq·day l−1) were proportional to the osmotic or ionic gradient but were inversely proportional to size. For 40-g fish, summed deviations were larger in 48 than in 0 ppt; for 120- or 260-g fish, these deviations were larger in 0 than in 48 ppt. These results indicate that small milkfish tend to adapt better to fresh than to hypersaline water while larger milkfish are more likely to find hypersaline water less stressful than freshwater. Like other organ systems previously studied in milkfish, these size-dependent adaptations in osmoregulatory mechanisms reflect natural habitat shifts during development.
    • Article

      Dietary supplemental effects of red seaweed Eucheuma denticulatum on growth performance, carcass composition and blood chemistry of juvenile Japanese flounder, Paralichthys olivaceus 

      JA Ragaza, S Koshio, RE Mamauag, M Ishikawa, S Yokoyama & SS Villamor - Aquaculture Research, 2015 - Wiley
      A 56-day feeding trial was conducted to determine the effects of supplementing diets of juvenile Japanese flounder, Paralichthys olivaceus, with Eucheuma denticulatum (EDP). Isonitrogenous and isolipidic test diets were prepared using a fishmeal-based positive control diet (PC) and a fishmeal-soy protein concentrate negative control diet (NC) supplemented with 3 (D3%), 6 (D6%) and 9% (D9%) EDP. The test diets were assigned to tanks (12 fish tank−1, initial mean body weight of 0.42 ± 0.01 g) in triplicates. Results of the feeding trial indicated that growth rates and feed efficiency significantly improved (P < 0.05) when 3% EDP was supplemented in the diets. However, there was a significant reduction (P < 0.05) of growth and feed efficiency in fish fed diets with higher supplementation levels. Protein, lipid, dry matter and ash contents of carcass and their corresponding nutrient retention values were not markedly altered in all dietary treatments. Fish fed diets supplemented with EDP exhibited higher (P < 0.05) omega-3 polyunsaturated fatty acid accumulation in dorsal muscle when compared with those of fish fed NC. Blood chemical parameters showed significant differences (P < 0.05) in total cholesterol and triglyceride levels. These results suggest that EDP can be efficiently utilized by Japanese flounder and can promote best growth and feed utilization at a level of 3%.
    • Article

      The effects of Vibrio anguillarum extracellular products on Japanese eels 

      MC de la Cruz & K Muroga - Aquaculture, 1989 - Elsevier
      To test the effect of Vibrio anguillarum extracellular products (ECP) on Japanese eels (Anguilla japonica ), test fish were injected intramuscularly with ECP at a dose of 1 mg protein/100 g body weight of fish.At 3,6,12,24 and 36 h post-injection, blood samples were collected for haematocrit, haemoglobin, and serum protein determinations and tissues were fixed in Bouin's solution. Histopathological observations 24 h post-injection revealed that the ECP caused severe damage to muscle tissue, characterized by extensive muscle liquefaction and haemorrhaging. In addition, extensive haemosiderin deposits were observed in the spleen, with lesser deposits occurring in the kidney and liver. Haematocrit, haemoglobin, and serum protein values were lower in ECP-treated fish than in the untreated controls.
    • Conference paper

      Hematological and histopathological changes in Oreochromis mossambicus after exposure to the molluscicides Aquatic and Brestan 

      ER Cruz, MC de la Cruz & NA Suñaz - In RSV Pullin, T Bhukaswan, K Tonguthai & JL Maclean (Eds.), The Second International Symposium on Tilapia in Aquaculture, 16-20 March 1987, Bangkok, Thailand, 1988 - Department of Fisheries; International Center for Living Aquatic Resources Management
      Duplicate static 96-hour bioassays were conducted to determine the median lethal concentration for Oreochromis mossambicus (LC50) of two organostannous molluscicides, commonly used in fishponds: Aquatin and Brestan. O. mossambicus was more sensitive to Brestan. The acute toxicity of both Aquatin and Brestan ceased towards the end of 96 hours. The 24, 48, 72 and 96 hour LC50’s were 4.01, 3.97, 2.95 and 2.58 ppm formulated product for Aquatin and 0.35, 0.18, 0.10 and 0.09 ppm for Brestan, respectively. The computed safe concentrations for Aquatin and Brestan are 0.30 and 0.01 ppm, respectively.

      Exposure to lethal concentrations of Aquatin resulted in an immediate reduction in hemoglobin and hematocrit levels. Hemoglobin content was likewise lower in Brestan-exposed fish, whereas their hematocrit level was higher than that of the control fish.

      Histological analyses of gills, intestine, liver and kidney showed pathological changes even in sublethal levels tested. Damage became severe with increasing concentration of the pesticide. The behavior and symptoms exhibited by the fish and the physiology of hematological and histopathological changes are discussed.
    • Article

      Testicular histology and serum steroid hormone profiles in hatchery-bred catfish Clarias macrocephalus (Gunther) during an annual reproductive cycle 

      JD Tan-Fermin, T Miura, H Ueda, S Adachi & K Yamauchi - Fisheries Science, 1997 - Japanese Society of Fisheries Science
      Testicular development, gonadosomatic index (GSI), and related steroid hormones (testosterone or T, 11-ketotestosterone or 11-KT, 17α, 20β-dihydroxy-4-pregnen-3-one or DHP) in serum were monitored during an annual reproductive cycle in tank-reared, hatchery-bred male catfish Clarias macrocephalus to established the season optimum for its artificial propagation. GSI values were highest in June (0.80%), and lowest in December, February, April (0.36%). At most times of the year, lobules in the testis and seminal vesicles were mostly lined with spermatogonia B (SGb) and spermatocytes (SC) and few spermatogonia A (SGa); spermatids (SD) and spermatozoa (SZ) were the least and most abundant of the spermatogenic cells, respectively. In January however, almost equal counts of SGa, SGb and SC were observed, as well as a significant increase in the percentage of SD and corresponding decrease in SZ. Serum 11-KT fluctuated at high levels, with the lowest level in January (159.42 ng/ml), and peak in September (434.72 ng / ml). Serum T levels ranged from 15-25 ng/ml, and were not markedly different throughout the annual cycle. Serum DHP levels were extremely low in January-May, and reached maximum levels in July (0.18 ng/ ml). Seasonal changes in the percentage of spermatogenic cells, GSI and serum steroid hormone profiles showed that captive, hatchery-bred male C. macrocephalus have a continuous reproductive cycle. Although milt release was not observed, males can readily be used as source of milt for artificial propagation at any time of the annual cycle, except in January.