Growth Of Rohu Research Articles

Dietary supplementation of probiotics improves survival and growth of Rohu (Labeo rohita Ham.) hatchlings and fry in outdoor tanks

Abstract Low survival (20–30%) and slow growth at early stages of Rohu, Labeo rohita have been major obstacles in meeting the demand of fry in Asia. Three experiments were conducted for 30 days each to evaluate the potential benefits of three multi-strain probiotics in three different stages of juvenile Rohu (hatchling—8 days old, fry—38 days old and advanced fry—68 days old) on the survival and growth. In this study, four different types of treatments were used; namely, T1: Control, i.e. feed without any dietary supplements, T2: feed with Lactobacilli, Bifidobacterium, yeast, Spirulina and phytase, T3: feed with Lactobacillus, yeast, seaweed and amylase, and T4: feed with Lactobacilli, Bacillus and yeast only. Hatchlings fed with T2 feed showed highest survival (74.7%), which is about 25% improvement in comparison to the survival of the Control group (49.9%). Similarly, T3 (60%) and T4 (61.5%) showed at least 10% increment in survival as compared to that of Control (T1). The hatchlings in T2 group had significantly higher (p 0.05) in final weight and specific growth rate among the treatments. Present study indicated that positive effects of multistrain probiotics on the survival and growth can be seen only at hatchling and fry stages, but not later stages.

Water Quality and Growth of Rohu, Labeo rohita, in a Biofloc System

We evaluated the technical feasibility of reducing water dependency of rohu, Labeo rohita, culture with biofloc under light-limited indoor culture. Biofloc and control treatments were conducted in 700-L indoor tanks at three different stocking densities (STD): 1.3, 2.6, and 3.9 Nos. fish m−2 of surface area of tank for a period of 90 days. In biofloc treatment, fish were fed 20% crude protein feed and extra organic carbon in the form of wheat flour, whereas in case of control treatment they were fed 30% crude protein feed only. Fish survival was 100% in both the treatments. Lower stocking density produced larger fish, but growth was similar within stocking densities among control and biofloc treatments. The nutritional quality of biofloc was found to be quite suitable for rohu. Frequency of water exchange was significantly less in biofloc treatments as compared to the control ones.

A comparative study of common carp ( Cyprinus carpio L.) and calbasu ( Labeo calbasu Hamilton) on bottom soil resuspension, water quality, nutrient accumulations, food intake and growth of fish in simulated rohu ( Labeo rohita Hamilton) ponds

The effects of two benthivorous fishes, common carp ( Cyprinus carpio) and calbasu ( Labeo calbasu), on bottom soil resuspension, water quality, nutrient accumulations, fish diet and growth of rohu ( Labeo rohita) were compared. In this study, individual tanks receiving bottom soil and water from a central pond were used to more naturally simulate rohu polyculture pond conditions. Two treatment combinations were performed in triplicate for 4 weeks: 6 rohu plus 3 common carp per tank and 6 rohu plus 3 calbasu per tank. Resuspension of bottom soil, free CO 2, and nitrogen and phosphorous concentrations in the water column were greater in the tanks with common carp while dissolved oxygen, pH, and total alkalinity were lower. Common carp increased the % nitrogen and % phosphorous accumulation in plankton and fish, while these nutrients were reduced in benthic macroinvertebrates and bottom soil. Gut contents of harvested calbasu contained a combination of benthic macroinvertebrates and zooplankton, rohu contained phytoplankton and zooplankton, and common carp contained almost entirely (82%) macroinvertebrates. Rohu shifted from zooplankton to phytoplankton when competition for zooplankton was higher in calbasu tanks. Since common carp preferred benthic macroinvertebrates they overlapped little with rohu for food. Common carp increased the harvesting weight and growth rate of rohu and thus had greater potential than calbasu to increase yields for rohu polyculture farmers.

Olive barb, Puntius sarana (Hamilton) is a potential candidate species for introduction into the grow-out carp polyculture system

The compatibility of olive barb, Puntius sarana (Hamilton) with major carps was studied in grow-out carp polyculture system for one year in a set of nine earthen ponds of 0.08 ha each. Three different species combinations evaluated were Control: catla (Catla catla Ham.), silver carp (Hypophthalmichthys molitrix Valenciennes), rohu (Labeo rohita Hamilton) and mrigal (Cirrhinus mrigala Hamilton) at 0.5:0.5:1:1; T1: catla, silver carp, rohu and olive barb at 0.5:0.5:1:1 and T2: catla, silver carp, mrigal and olive barb at 0.5:0.5:1:1 at combined density of 7500 fingerlings/ha. While survival levels of the carps did not differ significantly in treatments (P>0.05), silver carp recorded highest survival levels (94–96%) followed by olive barb (87–90%), mrigal (72–74%), rohu (72–73%) and catla (67–69%). The specific growth rate (SGR) and average harvested body weight (ABW) of catla and silver carp did not differ significantly among the treatments revealing their competition with mrigal or olive barb to be minimum. In absence of rohu in T2, both mrigal and olive barb showed higher SGR and ABW revealing minimal competition between these two species, while their lower performance in presence of rohu in Control and T1 indicated inter-specific competition with the latter. Such olive barb–rohu inter-specific competition, however, failed to yield significant effect on growth of rohu as revealed from its non-significant SGR difference in presence and absence of olive barb. The lower FCR (2.54±0.06) and higher treatment biomass production (3418.4±95.0 kg ha−1 year−1) in T1 with rohu–olive barb combination compared to T2 with mrigal–olive barb (2.84±0.11; 3155.1±104.7 kg ha−1 year−1) indicated feasibility and advantage of culturing rohu with olive barb rather than mrigal in carp polyculture. Further, similar biomass production in Control and T1 also indicated feasibility of replacing mrigal with olive barb in the grow-out carp polyculture system.

Effect of Varying Protein and Lipid Levels on the Growth of Rohu, Labeo rohita

Rohu (Labeo rohita, Cyprinidae) fingerlings (7.5 g) were fed six experimental diets containing two protein levels (25 and 30%) and three lipid levels (4, 6 and 9%) for 98 d. The best growth was obtained with the diet containing 30% protein and 6% lipid. At a given protein/fat level, increase in fat/protein resulted in better weight gain, except in the diet having 30% protein and 9% lipid. Protein efficiency ratio and net protein retention decreased with increase in dietary protein. Muscle RNA/DNA reflected the growth trend. Gut protease and lipase activity had a direct relationship with dietary protein. Dietary fat influenced carcass fat content, but dietary protein had no effect on carcass protein.

Influence of ontogenetic changes in prey selection on the survival and growth of rohu, Labeo rohita and singhi, Heteropneustes fossilis larvae

Influence of ontogenetic changes in prey selection on the survival and growth of rohu, Labeo rohita and singhi, Heteropneustes fossilis larvae

Influence of ontogenetic changes in prey selection on the survival and growth of rohu, Labeo rohita and singhi, Heteropneustes fossilis larvae

When offered a mixed diet of different zooplanktonic items covering a body size range of 75–2200 μm, (a) rohu, Labeo rohita and (b) singhi, Heteropneustes fossilis larvae ingested progressively larger prey as they grew, due to age‐related increase in gape. However, a nearly constant prey size/mouth size ratio was maintained for a period of 4wk after hatching. The dominance of rotifers in the diet during the first 2‐wk was followed by cladocerans, particularly Moina macrocopa. Significant differences observed in the growth rates of the larvae reared on different diet regimes were related to ontogenetic changes in prey selection. An exclusive copepod diet throughout resulted in the lowest weight gain in the larvae of both species. However, copepods had no apparent adverse effects when present with the preferred rotifers and cladocerans. Although constituting a suboptimal prey size for the older larvae, rotifers alone, when present in sufficient densities, produced growth rates comparable to those obtained on a cladoceran diet. However, a mixed diet regime contributed to the maximum growth. The implications of these findings to rearing larvae of the economically important rohu and singhi are discussed.