scholarly journals Effect of the combination of a cold water temperature and exogenous estrogens on feminization, growth, gonadosomatic index and fat muscle content of Nile tilapia Oreochromis niloticus (Linnaeus, 1758)

2019 ◽  
Vol 47 (1) ◽  
pp. 52-64
Author(s):  
Angol Lazaro Velasco ◽  
Helsi Isidro Cristobal ◽  
Juan Alcantar Vazquez ◽  
Carolina Antonio Estrada ◽  
Daniel Calzada Ruiz ◽  
...  
2020 ◽  
Vol 6 (3) ◽  
pp. 431-437
Author(s):  
Mohammad Ashaf Ud Doulah ◽  
SM Majharul Islam ◽  
Mohammad Shadiqur Rahman ◽  
Md Shariful Islam ◽  
Mohammad Harun Or Rashid ◽  
...  

The study was carried out to identify the parasite and causative diseases on cage reared tilapia at Bakerganj upazila, Barisal district. The infected tilapia fishes were collected from the cages and brought to the laboratory to find out signs, symptoms and infection area on the fish body. Physico-chemical parameters of water, such as water temperature, pH, dissolved oxygen, nitrate, phosphate and ammonia were monitored fortnightly. The values of water temperature (°C), pH, dissolved oxygen (mg/l), nitrate (mg/l), phosphate (mg/l) and ammonia (mg/l) were 32.4±2.1, 6.2±0.3, 7.52±0.4, 0.028±.008, 11.30±2.26 and 0.09±0.02, respectively but the concentration of nitrate was so higher during the study time. Eleven species of parasites namely, Chilodonella sp, Trichodiniasp., Gyrodactylussp.,Cichlidogyrus sp., Capillariasp, Orientocreadium sp, Eustrongylidae sp, Allocreadium sp, Euclinostomum sp, Tylodelphys sp. and Metagonimus spwere were identified. Parasites were found on all the examined parts of the fish body but gill showed the most infested area of the host. Highest mortality rate was occurred in the month of October and lowest mortality rate was in July. In this circumstance, proper management system and handling are best ways to prevent diseases and reduce the mortality rate of tilapia on cage farming in the southern area. Res. Agric., Livest. Fish.6(3): 431-437, December 2019


2010 ◽  
Vol 17 (3) ◽  
pp. e683-e690 ◽  
Author(s):  
S. XIE ◽  
K. ZHENG ◽  
J. CHEN ◽  
Z. ZHANG ◽  
X. ZHU ◽  
...  

2008 ◽  
Vol 65 (7) ◽  
pp. 1413-1424 ◽  
Author(s):  
Jeppe Kolding ◽  
Lise Haug ◽  
Sigurd Stefansson

Growth, size at maturity, gonadosomatic index (GSI), egg size, and absolute fecundity of Nile tilapia ( Oreochromis niloticus ) were significantly affected by oxygen levels (1.5 ± 1.0, 2.8 ± 1.4, and 6.0 ± 1.8 mg·L–1) in a controlled experiment designed to test the hypothesis (D. Pauly. 1984. J. Cons. Int. Explor. Mer, 41: 280–284) that O2 is the controlling factor for the transition from juvenile to adult in fish, in general, in the context of phenotypic life history plasticity and “stunting” in tilapias. Size at maturity and the estimated asymptotic size decreased with decreasing O2 concentration, as predicted by Pauly’s hypothesis. All fish matured at the same age (18 weeks old), which is in contrast to conventional definitions of stunting. This finding challenges the suggested plasticity in age at first maturity for tilapia. The results also challenge the hypothesis that stunting is a unique recruitment mechanism, as the smaller fish in the group with low oxygen concentration produced smaller and fewer eggs than the larger fish in the group with high oxygen concentration.


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