The distinctive developmental stages of common carp are described in Table 1. Their durations depend on:
- environmental conditions: climate, water temperature, water quality and the availability of food; and
- culture conditions: density of fish, natural food productivity/production of pond and applied feeds (Table 1).
Under tropical conditions, common carp grows continuously, but in the temperate zone the growth is interrupted by winter, as well as by the colder months of autumn and spring. For this reason, the net duration of the production season is within the period when common carp intensively feeds and grows; i.e. when the water temperature is above 18–20 oC.
The growth rate, being the most important quantitative trait, is the main focus of breeding programmes, which are mainly based on crossbreeding to achieve quick improvement of growth performance (heterosis affect) in the F1 generation. This technique is widely used in Hungary, Israel, the Czech Republic, Poland and other countries (Flajshans and Hulata, 2006).
The growth potential of common carp is enormous. If the water temperature is suitable, its many forms and strains can attain an individual weight of about 0.2–0.3 kg, 1–1.2 kg and 2.5–3.5 kg within about 2–3, 5–7 and 10–14 months, respectively. Still, the economically feasible individual weights of the different age groups of common carp are about 0.025–0.05 kg/fingerling, 0.25–0.5 kg/grower and 1.2–1.8 kg/table fish (Antalfi and Tölg, 1971; Tasnádi, 1997).
About 15–30 days are required for the feeding larvae to grow into advanced fry (Table 1). The next life stage, when the fish grows up to become a fingerling, lasts about 45–85 days.
The size of table fish of common carp varies from country to country and may be anywhere between 0.25 and 3 kg (Figure 9). If the table fish is larger than 1 kg, the on-growing is done in two steps. In the first step, fish are stocked in higher density to grow up to a size of 0.25–0.50 kg, while in the second step fish are further reared in order to obtain a size of about 1–3 kg. Both steps last about 120–170 days (Table 1 and Figure 7).
