Growth pattern and daily growth increment in lanternfish (Benthosema pterotum) of the Oman Sea

Lanternfish (Benthosema pterptum) is one of the most important fish species in the Oman Sea. We randomly sampled 300 myctophids from different depths in spring and winter 2009 in the Oman Sea using mid-water trawls. Male to female sex ratio was 0.36:0.64. The thin sections (60-80µm) of sagitta otoliths of the fish were prepared using polishing method. These sections showed that increment growth rings of lanternfish otolith are formed daily and the age condition is distinguishable on a daily basis. We found the life span of the species to be short (with a maximum of 349 micro-increments counted) and probably less than a year. The relationship between standard length (SL) and daily growth increment (D) was expressed as the linear equation: SL=0.87D+12.37 (R 2=0.97). The relationship between lanternfish weight (W) and daily growth increment (D) was expressed as power equation: W=0.00003D1.754 (R2=0.95). Furthermore, morphometrical characteristics of otolith including otolith weight and length and daily growth increment relationships were expressed as linear equation (R2=0.96 and R 2=0.83). The results showed that lanternfish growth rate were in the range 0.241mm/d-1 to 0.138mm/d-1 and decreased by body size and age in this range

Endocrine disrupting effects of 4-nonylphenol on plasma vitellogenin, reproductive system and histology in koi carp (Cyprinus carpio)

This study aimed to assess the effect of 4-nonylphenol (4-NP), a ubiquitous aquatic micro-chemical pollutant substance on some on some reproductive parameters and histology in koi carp. Fish were intraperitoneally subjected to ascending doses of 4-NP at 10, 50 and 100 μg/g body weight (BW) on days 7, 14 and 21 after the initiation of the experiment. Also, one group was treated with 17β-estradiol (E2) at 2 μg/g BW, positive control group (C2) received the vehicle (50 μL of coconut oil + 50 μL Ethanol) per fish and a negative control group (C1) was considered without injection. The results showed that 4-NP induced significantly an increase in E2, progesterone, and plasma vitellogenin at 50 μg/g in both male and female, while level of testosterone significantly decreased in the treated fish compared to control fish (P < 0.05). Conversely, the levels of these parameters at the higher concentration of 4-NP (100 μg/g) were significantly reduced compared to control one (P < 0.05). Also, some sever histopathological changes were observed in ovary, testicular and liver of treated fish, reflecting fish sensitivity to 4-NP at higher doses. This study showed that 4-NP has an estrogenic potency in the sexual development, hepatotoxicity and gonado-toxicity of koi carp

Adjuvant effects of medicinal herbs and probiotics for fish vaccines

The most prominent limiting factor in aquaculture nowadays is infectious diseases as they lead to massive economic losses. These diseases are often partly controlled by vaccination, herbs or probiotics. Despite the fact that vaccination is the most effective prophylactic approach to disease prevention, researchers have started to use plant-derived products and probiotics as adjuvants to boost the efficacy of fish vaccines. This review describes the efficacy and potency of plant extracts/essences and probiotics as adjuvants for various vaccines in aquaculture

Effect of the probiotic, Lactobacillus plantarum on growth performance and haematological indices of rainbow trout (Oncorhynchus mykiss) immunized with bivalent streptococcosis / lactococcosis vaccine

The present study evaluated the effect of Lactobacillus plantarum as a probiotic on the growth performance and haematological parameters of juvenile rainbow trout (Oncorhynchus mykiss) weighing 29.6±1.8 g immunized with streptococcus/lactococcus bivalent vaccine for 60 days at 16±1.5ºC. Fish were randomly allocated to 4 equal groups: probiotic (g kg-1 feed equal to 108 cells g-1) supplemented diet group (group P), vaccinated fish fed with a normal diet (group V), vaccinated fish fed with probiotic (group P+V) and unvaccinated fish fed normal diet (group C). Results showed that weight gain, final weight, condition factor and thermal-unit growth coefficient were improved in P+V group compared with other groups but was significantly different from groups V and C (p0.05) was found in RBC, Hb, MCH, MCHC and MCV levels among the different experimental groups. These data show that application of L. plantarum could be a benefit of vaccinated trout, enhancing fish growth and haematological parameter

The effect of Perilla ( Perilla frutescens)

The effects of Perilla frutescens leaf extract (PLE) on the quality of surimi fish balls were investigated in the present study. Firstly, the extract was prepared by solvent extraction using 95% ethanol. Then, the phenolics in the extract were analyzed by instrumental analysis. The total phenolic content in the PLE was found to be 14.51 mg gallic acid equivalent (GAE)/g dry weight (DW). The amount of caffeic acid, ferulic acid, rosmarinic acid, quercetin, and apigenin, determined by high‐performance liquid chromatography (HPLC), was 4.80, 5.10, 2.95, 6.46, and 3.93 mg/g DW, respectively. Furthermore, the PLE was found to show high free radical scavenging activity toward DPPH and ABTS radicals with IC50 values of 12.15 and 7.26 μg/ml, respectively. When PLE was fortified into surimi fish balls at 0.03% and stored at 4°C, it was found to slow down lipid and protein oxidation during storage of surimi fish balls as evidenced by the significant reduction in TBARS values and protein carbonyl contents (p &lt; 0.05). PLE (0.03%) also decreased the formation of total volatile basic nitrogen (TVB‐N) and inhibited the growth of E. coli compared with the control group (p &lt; 0.05). In addition, the overall acceptability of PLE‐added (0.03%) samples was higher than control samples during the storage process (p &lt; 0.05) by sensory analysis. Overall, PLE have the potential to be used as a natural food additive to improve the shelf life and sensorial qualities of surimi fish ball