Clinical And Pathological Investigation Of Psychrobacter Immobilis Infection In Rainbow Trour (Oncorhynchus Mykiss, Walbaum)

The pathogenicity of Psychrobacter immobilis, isolated from naturally infected rainbow trout Oncorhynchus mykiss, was investigated. In experimentally-infected trout, no mortality was recorded during 35 days but the following external and internal symptoms were observed. Externally, skin was darkened, gills were pale and swimming was abnormal. Internally, there were dilatations of the vascular structures on cross-sections of the liver; vascular congestion, inflammatory mononuclear cell infiltration and degeneration in the gills; interstitial inflammatory mononuclear cell infiltration and free bleeding in patches of the posterior kidney; vascular con- gestion and free bleeding in the spleen; degeneration, atrophy, polymorphonuclear leukocyte infiltration and liquefaction necrosis in muscle fibers; edema, inflammatory mononuclear cell infil- tration and basophilic degeneration among muscle fibers of the heart; and congestion in vascu- lar structures on cross-sections of the brain tissue. It is suggested that P. immobilis is an oppor- tunist pathogen that causes secondary infections

Authentication of fish species using a simple PCR-RFLP method

A polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method was developed as a tool to prevent commercial frauds in fish products. The PCR was used to ampli- fy the cytochrome b gene, part of the mitochondrial genome. The PCR products were digested with different restriction endonucleases (AluI, HaeIII, HinfI, Hsp92, Taql) to identify five fish species - Mugil cephalus, Pomatomus saltator, Belone belone, Merlangius merlangus, and Oncorhynchus mykiss. None of the tested enzymes, alone, was able to distinguish between the five fish species, but by combining the results of two digestions, all five species could be differ- entiated. Thus, this method can be used to expose fraudulent substitutions with less valuable fish

The Effects of Different Sized Granules and Particle Composition on Growth of Rainbow Trout (Oncorhynchus mykiss)

Three feeding regimes were tested to determine their effects on growth, survival, and feed conversion in rainbow trout alevins for 60 days. In the first regime, the alevins were fed a starter feed consisting of 800 micron parti- cles for the first 15-day period. For the following 15-day period, the alevins were given a starter feed consisting of 1200 micron particles. For the final two 15-day periods, the alevins were given feeds consisting of 1500 micron and 2 mm particles, respectively. In the second regime, feed particles in the four periods were 1200 micron, 1500 micron, 2 mm, and 3 mm granules, respectively. In the third regime, feeds contained 1500 micron, 2 mm, 3 mm, and 4 mm granules. During the first two 15-day periods, no significant dif- ferences in growth parameters were detected (p>0.05). In the second two 15-day periods, there were significant differences in final live weight, growth, and feed conversion rates between groups (p0.05)

Early Development And Growth Of Arctic Charr (Salvelinus Alpinus) And Rainbow Trout (Oncorhynchus Mykiss) At A Low Water Temperature

Hatchery traits and growth of eggs and fry of rainbow trout, Oncorhynchus mykiss, and arctic charr, Salvelinus alpinus, were tested in fresh water of a low temperature. There were significant differences (p<0.05) between the survival rates from fertilization through the eyed stage and the first exogenous feeding. No significant differences were observed between species with regard to feed conversion or survival of fry at the end of the 154-day trial, but weight gain and specific growth rate differed significantly (p<0.05). These results suggest that the arctic charr could be considered an alternative to rainbow trout, particularly in coldwater farms

Effect Of Photoperiod On Plasma Thyroxine Hormone Level Of Mirror Carp (Cyprinus Carpio) Raised At A Low Water Temperature In A Controlled Environment

The objective of this study was to examine the effects of various lighting regimes on the plasma thyroxin hormone (T4) level of mirror carp (Cyprinus carpio). The carp were kept at the low tem- perature of 9°C to eliminate any influence of water temperature on feed intake, growth, and the hormone level. Treatments were 8 h light:16 h dark, 12 h light:12 h dark, and 16 h light:8 h dark. Plasma thyroxin levels were measured every four weeks for 12 weeks. The levels were signifi- cantly higher (p<0.05) in the groups exposed to 8 or 12 h light than in the group exposed to 16 h. The T4 levels significantly dropped with time in all photoperiods