High density rearing of rohu,Labeo rohita(Hamilton) from spawn to fry in concrete tanks: effect of daily feed ration and soil base on fry growth and survival

Abstract

Rearing of rohu spawn to fry size was carried out at high density (2000 spawn m−2) in large concrete nursery tanks (10 m × 5 m × 1.2 m) to standardize the daily ration of supplementary feed and to assess the impact of soil base on the fry performance. In Set‐1, supplementary feed was provided at 100% (control), 75% and 50% of the daily ration that is commonly used in earthen carp nursery ponds and named as the three treatments T‐1, T‐2 and T‐3 respectively. Although in Set‐II, performance of fry were evaluated in tanks provided with and without soil base. The fry survival was to the tune of 45–59% at this high density of 2000 spawn m−2, indicating the efficacy of the concrete nursery system for high density seed rearing. In Set‐I, T‐2 receiving 75% of the control ration exhibited similar fry growth as that of T‐1, but its fry survival (58.8%) was 10% higher than the latter. This indicated that supplementary feed in a concrete nursery can be reduced up to 25% of that provided in earthen nursery system while ensuring a higher fry yield. However, further reduction up to 50% of the control ration in T‐3 yielded lower fry survival and growth (P < 0.05) revealing inadequacy of the available feed. In Set‐II, treatment without soil base (T‐ns) yielded similar fry growth but 10% higher survival compared to that with the soil base (T‐s) revealing non‐essentiality of soil base in concrete tanks for such short‐term nursery rearing of rohu.

Role of fertilization, supplementary feeding and aeration in water quality changes and fry growth in intensive outdoor nursing of fringed lipped carpLabeo fimbriatus(Bloch)

“…All the water quality parameters in T‐1 were within the suitable ranges, as reported earlier in carp nursery (Basavaraja & Antony, 1997; Das et al, 2016; Jena et al., 2005), which eliminated the cause of any water quality‐related stress to lower its fry growth. It also indicated inadequacy in dietary energy supplementation through plankton for the densely stocked fry in T‐1, attributed to starvation.…”

“…This caused an increase in the BCR and significant rise in the profit margin ( p < .05) in T‐2 (Table 3), attributed to the use of supplementary feed. The authors have earlier reported a BCR of 4.47 in rohu reared at 2000 spawn m‐3 with similar level of supplementary feeding in concrete nursery system (Das et al., 2016). Similarly, with aeration as additional input, T‐3 not only had better water quality prevalence, but also produced fry which were 31% higher by number and 44% higher by biomass than T‐2, while its fry size was similar to that of the later.…”

“…Tanks were divided into three treatment groups, each with four replicates, to receive varied input combinations such as only fertilizer (T‐1); fertilizer + supplementary feed (T‐2); and fertilizer + supplementary feed + aeration (T‐3). Powdered mixture of rice bran and groundnut oil cake (1:1 ratio) was fed to the larvae of T‐2 and T‐3 groups at 225 g tank −1 (@4500 g/day for every million spawn (Das, Jena, & Patro, & B. Mohanta, D., 2016) during the first week, 450 g tank −1 in the second week and 600 g tank −1 in subsequent 15 days of rearing. The daily ration was fed in two meals in the morning (07:00–08:00 hr) and afternoon (16:00–17:00 hr).…”

Optimising water requirement for nursery rearing of rohu Labeo rohita (Hamilton, 1822) in large outdoor concrete tanks: influence of water depth on seed performance

“…The usual daily ration of supplementary feed is provided at approximately 400% of initial spawn biomass (6 kg per million spawn) on day 1 and subsequently doubled and tripled on day 6 and day 11, respectively (Jena and Das, 2011). However, Das et al (2015) observed similar growth performance for fry fed at 75 and 100% of the above mentioned ration and recommended the former, thereby saving good amount of supplementary feed. Similar attempts have also been made over the years to modify use of various other inputs to refine the carp seed production technology (Jena et al, 1998;Das et al, 2015;Kamble et al, 2017).…”

“…However, Das et al (2015) observed similar growth performance for fry fed at 75 and 100% of the above mentioned ration and recommended the former, thereby saving good amount of supplementary feed. Similar attempts have also been made over the years to modify use of various other inputs to refine the carp seed production technology (Jena et al, 1998;Das et al, 2015;Kamble et al, 2017). Apart from fertilisation and supplementary feeding, depth of water in nursery also plays a significant role on the growth performance of the fry.…”