Growth of organs and tissues in carp (Cyprinus carpio L.) larvae.

Growth of some internal organs and tissues was studied in carp (Cyprinus carpio L.) in order to provide baseline information on the growth process during the first posthatching stages of fish, and to compare the trend observed in fish to that known in other animals. Growth of organs and tissues (liver, pancreas, trunk muscles, digestive tract, eyes, nervous system) was studied in rapidly growing carp (Cyprinus carpio L.) larvae by means of a quantitative histological method. Mean body weight of carp larvae rose from 1.8 mg at 2 days to 50.4 mg at 18 days. Between 4 and 18 days after hatching (yolk exhausted; exogenous food only), the average specific growth rates of organs were around 31% per day for the liver and pancreas, 28% per day for the trunk muscles, 26% per day for the digestive tract (without lumen) and 19% per day for the eyes and nervous system. Compared to the total volume of tissues, liver (k = 1.19), pancreas (k = 1.19), and trunk muscles (k = 1.09) showed positive allometry, digestive tract showed isometry (k = 1.00), and eyes (k = 0.76) and the nervous system (k = 0.73) showed negative allometry. This study demonstrated that the growth process of some organs (i.e. liver, pancreas and digestive tract) is different between larval and older stages of carp, and that the development of carp larvae exhibit the same order of allometry coefficients as do certain mammals (e.g. rabbit and lamb) in their early postnatal stages: nervous tissue, digestive tract, muscular tissue, liver.