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Fish larvae have a high requirement of amino acid (AA) for energy production and growth. This study was aimed to increase knowledge of AA profile during feral carp larval ontogeny and estimate larval AA requirements. Larvae were collected randomly at 1, 3, 7, 11, 15, 19, 26 and 33 days post hatch for growth and AA analysis. The composition of total AA changed significantly during ontogeny. The essential AA profile of marine carp showed low correlation with rotifers (R²₌0.22). High correlation was found between dry food and early larval ages (R²≥0.7) but was lower in late stage (R²≥0.37). At day 7, when larvae were fed on rotifers, methionine seemed to be the limiting AA and when larvae were fed dry food at day 11, 15, 19, 26 and 33, arginine seemed to be the limiting AA. Larval indispensible AA profile can be used as index of the IAA requirements of carp larvae. Supplementation of larval diet used with limiting AA is one way for compensating the deficient amino acid.

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The present study was conducted in Electric Blue Cichlid Sciaenochromis fryeri in early larval developmental stages from the fifth day post hatching (DPH) until 51 DPH to determine day of transforming from embryo to juvenile. Morphological characteristics were evaluated by using ImageJ software. Allometric growth patterns were calculated based on the formula Y=aX^b. Yolk sac depletion was occurred on day 9. Scales were developed on day 19 and finaly developed juvenile shape. allometric pattern of different body segments were calculated according to isometry, positive, and negative allometry. Positive allometry of head and tail prior to inflexion point and variation in allometric growth pattern in different body segment determine priorities of organogenesis for survival in fish early life history. The obtained results showed consistency between the larval morphological changes and development of organs related to sensory movements and larval behavior. Every morphological change in larvae displays the development and evolution of one of the organs involved in feeding, breathing, swimming and sensory organs.