Summer mid-day-night composition and abundance of zooplankton from Lake Ikeda, Japan

Variations between midday and midnight in the species composition and abundance of the main zooplankton assemblage of Lake Ikeda, a crater-lake were analyzed during the summer of 1986. The protozoans, comprising more than 70% of the whole zooplankton population were the most abundant followed l7y the rotifers (12%), eopepods (8 %) and cladocerans (7 %). Except for the copepods and a few rotifers, most of the other zooplankton were evident at a slightly higher abundance at night. Total zooplankton abundance was highest during early summer but decreased gradually until the end of summer. Species composition was highest in early summer, and persisted until the middle of summer but gradually decreased with rare occurrences of some species at the end of summer, where some species were either rarely sampled or entirely absent from the samples

Effect of mushroom supplementation as a prebiotic compound in super worm based diet on growth performance of red tilapia fingerlings

A feeding trial was conducted to investigate the effect of mushroom supplementation as a prebiotic compound in an insect-based diet on the growth performance and feed utilization of red Tilapia (Oreochromis sp.). A total of 120 fingerlings were divided in triplicates for each treatment. Four experimental diets were offered to the fishes within a 56 days treatment period. Out of the four diets, three contained mushroom stalk meal (MSM) supplementation at various levels of inclusion of prebiotic compound (0.5% MSM; 1.0% MSM; 1.5% MSM) and the fourth a control diet without MSM inclusion. During the growth test, fish receiving diet containing prebiotic showed significantly higher (p0.05) were observed in whole body protein and ash contents among the fish feeding on these diets. All water quality parameters showed no significant difference (p>0.05) in all treatments. The result of this feeding trial indicated that the 10% supplementation level of MSM as a prebiotic for tilapia could be used in the insect-based diet, Zophobas morio

Effect of partial and complete replacement of fishmeal with mushroom stalk meal and soy bean meal on growth performance of Nile Tilapia, Oreochromis niloticus fingerlings

A dietary study was conducted to assess the use of mushroom stalk (MM), Pleurotus sajor caju, an agriculture waste and soy bean meal (SBM) as partial and complete replacement of fishmeal (FM) in tilapia fingerling diets. The study was conducted for 56 days. The diets were processed into sinking pellets. The experimental diets were formulated to replace fish meal protein at 0, 33, 67 and 100% (diet 4, 3, 2 and 1). In this experiment, Nile tilapia fingerlings weighing about 1.00 g were fed each of four isonitrogenous diet. They were randomly distributed into 12 plastic tanks with each tank stocking 20 fish. The experiment was conducted in three replicates for each treatment. All the diets were well accepted by the fish. No physical abnormalities were observed in all treatments. Good growth performance was shown in 33% replacement (diet 3) of FM diet. However, diet 1 (100% replacement) gave the highest increment in crude protein level and the best result of feed conversion ratio (FCR) and protein efficiency ratio (PER). Furthermore, the 100% replacement of FM (diet 1) was the best with a production cost of RM2.61/kg

Growth performance, feed utilization and body composition of Nile tilapia, Oreochromis niloticus (Linnaeus, 1758) fed with different levels of black soldier fly, Hermetia illucens (Linnaeus, 1758) maggot meal diet

In this study, fish meal (FM) was replaced by the black soldier fly maggot meal (BSFM) with replacement levels at 0%, 25%, 50%, 75% and 100%. The feeding trial was conducted for 56 days and the effect of each replacement level on the growth performance, feed utilization, body composition and survival of the experimental fish was assessed. All the experimental diets were well accepted by the fish. No mortality was observed during the experimental period. Diet 3 resulted in the highest weight gain and SGR values of 8.74±0.18 and 2.43±0.04% respectively. FCR and PER values obtained for Diet 3 were also better compared to that with other diets. Although there were no significant differences in crude protein content among fishes fed different diets (Diet 1 to Diet 5), fish fed Diet 3 showed significant (p<0.05) increase in crude protein content at the end of the experiment. Based on these results, it may be concluded that BSFM can be used to replace FM with up to 50% replacement without causing adverse effects on growth and feed utilization parameters

Fishmeal replacement with Spirulina Platensis and Chlorella vulgaris in African catfish (Clarias gariepinus) diet: Effect on antioxidant enzyme activities and haematological parameters

This study explored fishmeal replacement with two freshwater microalgae: Spirulina Platensis and Chlorella vulgaris in African catfish (Clarias gariepinus) diet. The effect of inclusion of the two microalgae on biomarkers of oxidative stress, haematological parameters, enzyme activities and growth performance were investigated. The juvenile fish were given 3 distinct treatments with isonitrogenous (35.01–36.57%) and isoenergetic (417.24–422.27 Kcal 100 g−1) diets containing 50% S. platensis (50SP), 75% S. platensis (75SP), 50% C. vulgaris (50CL), 75% C. vulgaris (75CL) and 100% fishmeal (100% FM) was used as the control diet. The result shows that all the diets substituted with both S. platensis, and C. vulgaris boosted the growth performance based on specific growth rate (SGR) and body weight gain (BDWG) when compared with the control diet. The feed conversion ratio (FCR) and protein efficiency ratio (PER) was significantly influenced by all the supplementations. The haematological analysis of the fish shows a significant increase in the value of red and white blood cells upon supplementation with 50SP and 50CL but decrease slightly when increased to 75SP and 75CL. Furthermore, the value of haematocrit and haemoglobin also increased upon supplementation with 50SP and 50CL but decrease slightly when increased to 75SP and 75CL. The white blood cell (WBC), red blood cell (RBC) increased, while total cholesterol (TCL), and Plasma glucose levels decreased significantly upon supplementation of algae. This is a clear indication that S. platensis and C. vulgaris are a promising replacement for fishmeal, which is a source protein in the C. gariepinus diet

Inclusion of cricket (Gryllus bimaculatus) meal in African catfish (Clarias gariepinus) feed influences disease resistance

In our present study, we observed the effect of cricket meal (CM) on disease resistance of African catfish. Fish were fed diets containing 350 g kg–1 and 400 g kg–1 of CM and 350 g kg–1 of fishmeal as control. The fish were divided into triplicates treatments of ten fish per replicate, weighed 22.5±0.6 g and fed with experimental diets for 40 days before being challenged against Aeromonas hydrophila. Relative percentage of survival (RPS) was recorded over 12 days post-challenge. White blood cell count, total protein, globulin and lysozyme showed significantly increasing levels in those fed with cricket meal diet compared to the control group. Mortalities at 12-day post-challenge significantly decreased to 30% (RPS: 66.7%) and 27% (RPS: 70%) for 35% and 40% CM respectively compared to 90% mortality in control group. Intestines and liver tissues of infected fish were dissected for pathogenic confirmation. The intestines of control diet showed the highest bacterial load (58.2×107 cfu g–1) compared to CM diets. The current study indicates that dietary CM could enhance the innate immune system and disease resistance of African catfish

Cyclomorphism in Bosmina longirostris (Crustacea:Cladocera) from Lake Ikeda, Japan

Zooplankton were sampled in Lake Ikeda at a fixed station every month with the aid of a plankton net in order to observe whether cyclomorphism was exhibited by the neonates of Bosmina longirostris. In Lake Ikeda the relative sizes of the antennules and mucrones of B. longrostris neonates decreased in relation to carapace length from 65% in winter to 50% in summer. Mucrone lengths also decreased from 30% in winter to 20% in summer. Both appendages were inversely correlated with surface temperature of the lake. Predation seems to be one of the reasons why neonates of B. longirostris exhibited seasonal cyclomorphism in their antennule and mucron

Rate of recolonization of the major arthropoda taxa inhabiting saraca roots in a tropical mountain stream

A study of the major Arthropoda taxa of invertebrates recolonizing Saraca roots occurring on various substrates and under various water velocities was carried out in the upper reaches of the Gombak River. The sites for the recolonization experiments were selected in the fast and slow flowing sections of rocks and boulders, sand and gravel and mud and silt biotopes. The Hydropsychidae and the Nemouridae were the pioneer recolonizers of Saraea roots in the fast flowing sections of the stream whereas the Ptilodactylidae and the Caenidae were the pioneer recolonizers in the slow flowing sections of the stream

Reporter gene expression in Transgenic Tilapia, Oreochromis niloticus(L.)

The purpose of this study was to analyse the expression of a reporter gene, lacZ spliced to a ubiquitous carp β-actin promoter in transgenic tilapia, Oreochromis nilotricus (L). Since lacZ is not diluted by cell division, it would serve as a genetic marker. Cells that express lacZ can be easily identified histochemically by reacting it with X-gal that produces a blue colouration on reaction with the enzyme β-galactosidase (product of lacZ gene expression).Transient expression assay using the carp β-actin construct in GO microinjected tilapia embryos revealed that the expression was very mosaic. This is obviously the result of mosaic distribution of the transgene. All the cells/tissues/organs examined are able to express lacZ but do not do so at the same time in any one embryo. The level and extent of lacZ expression varied considerably among individuals.In the stably integrated germ-line transmitted tilapia (C86, C118 and C58 line), expression level varied between each transgenic line according to their copy numbers.In the C86 line, it was possible to obtain 100% of lacZ expressing hemizygous progeny from putative homozygous fish when crossed with wild type. However in the C118 line, an average of 80% of lacZ expressing hemizygous embryos were obtained. This could be the outcome of unequal recombination during meiosis.Apart from investigating the variable expression in embryos of C86 and C118 line, both lines were also used to generate triploid transgenic fish through heat-shock induction. The females were sterile through disruption of gonads while a proportion of the males could still be reproductively functional.</p