Clarias macrocephalus or the female walking catfish is one of widely present fish across Asia. This fish has been commercially cultivated in Thailand due to its tender flesh and appetizing flavor1. Despite its likeability by local people, the production is limited due to the introduction of catfish hybrids and decreasing habitat due to urbanization and over-exploitation2.
For commercial farming of catfish, sexual maturity timing and successful spawning program are imperative. Many programs have been developed to speed up the sexual maturation in cultured catfish counting hormonal and environmental changes as well3.
Among the environmental factors photoperiod is one of the important one that regulate the reproductive cycle, according to previous studies, manipulating the photoperiod may affect the sexual maturation4.
Melatonin is an indol-amine hormone regulating the wakefulness, synthesized in the pineal gland and is controlled by the photoperiod. During the night cycle, two enzymatic steps allow the formation of serotonin (neurotransmitter) from tryptophan (Alpha amino acid)5.
Melatonin receptors are found in the ovary, brain and other peripheral tissues. The direct effect of melatonin receptor mechanism is by its metabolites, functioning as direct scavengers of free radicals and an indirect antioxidant6. Melatonin is involved in the reproductive processes through the hypothalamus-pituitary-gonadal endocrine axis7.
Recently, melatonin and zinc amino acid in separate treatment showed significant improvement towards the maturation of female and male catfish. In order to further understand the influence of melatonin and ZnAA in female cat fish, researchers conducted another study. They investigated the optimum level of combined melatonin and zinc amino acid treatment to enhance the female C. macrocephalus brood stock maturation and reproductive performance8.
For this purpose the researchers took the varied zinc amino acid levels and melatonin were mixed in the diet comprised of crude protein and crude lipid and were fed to the female catfish. Zinc accumulation, maturation analysis, breeding performance and immune analysis were evaluated.
The results of this study revealed that the combined zinc amino acid and melatonin treatment significantly increased the maturation parameters and reproductive performance. There was also a significant increase in hematological parameters within the combined zinc amino acid and melatonin treatment such as red blood cell count and haematocrit.
Authors of study conclusively said that:
“Our study recommended the combined zinc amino acid and melatonin treatment of dosage of 200 ppm zinc amino acid and 50 mg kg–1 melatonin (MZn2) to enhance the female maturation of C. macrocephalus.”
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17 November, 2019