Advances in Aquaculture and Fisheries Management

Advances in Aquaculture and Fisheries Management Vol. 2 (8), pp. 187-191, August, 2014. © International Scholars Journals

Full Length Research Paper

Resulting effects of substitute for fish-meal with crab-meal on growth and feed use of African giant catfish

(Heterobranchus longifilis) fingerlings

Alomiri R. Ayo

Department of Marine Sciences, University of Lagos, Akoka. Lagos, Nigeria. E-mail: [email protected]

Accepted 27 July, 2014

Abstract 

A feeding experiment was conducted in plastic aquaria (46 × 38 × 28 cm³) to investigate the effect of replacing fish-meal (FM) with crab-meal (CM) on growth, feed utilization and body composition of Heterobranchus longifilis fingerlings with body weight, 3.11 ± 0.56 - 8.48 ± 1.70 g and total length, 73.07 ± 4.99 - 98.69 ± 7.64 mm. Fish and crab-meal were separately used to produce feeds containing 30, 35 and 40% crude protein (CP) and fed to fish for 10 weeks at 5% body weight. The results show that fish fed with 40% CP fish-meal diet had the best growth as indicated in mean weight gain, 6.99 ± 1.70 g; specific growth rate, 4.05 ± 0.19% day^-1; feed conversion ratio, 1.12 ± 0.06 and protein efficiency ratio of 2.28 ± 0.12. Diets with FM performed better than CM diets. Percentage survival rate for FM and CM containing diets varied between 91.0 ± 1.63 and 100% and the condition of fish was not significantly different (P > 0.05). Apart from whole body levels of CP in FM fed fish, moisture and fat contents were unaffected by dietary treatments. Deficiency in some essential amino acids and higher dietary ash levels in CM probably impaired effective utilization of these diets compared to FM. Crab-meal diets show appreciable performance and could have potential use as a partial replacer of FM at a particular level.

Key words: Heterobranchus longifilis, fish-meal, replacement crab-meal, growth, food utilization.

Advances in Aquaculture and Fisheries Management Vol. 2 (7), pp. 171-175, July, 2014. © International Scholars Journals

Full Length Research paper

Cross-reactive fish allergen with special steadiness: Parvalbumin

Jatan Imtiyaz and Husen O. Barot

Department of Fish Extension Education, Faculty of Agriculture, Himachal Pradesh University, Summer Hill, Shimla, Himachal Pradesh, India. E-mail: [email protected]

Accepted 05 June, 2014

Abstract

Parvalbumins (PVs) form a major part of the fish skeletal muscle sarcoplasm, and were identified as the major cross-reactive allergens in a variety of fish species. Therefore, the intake of fish or fish-linked products may cause serious clinical problems. It is known that the biochemical and structural characteristics of a protein play a central role in determining its potential functions. This study is sought to evaluate the stability of PV’s structure which would be the foremost reasons in keeping them responsive yet after cooking. Here, PVs obtained from a commonly consumed fish Channa marulius were used as the test protein. The protein, PV turned out to be fairly resistant to high temperatures (90°C) and set on in a typical single band of 10 kD in SDS-PAGE. This suggests that following heating only partial and /or reversible loss of PV structure occurred, which rendered it allergenic to predisposed individuals.

Key words: Parvalbumin, allergen, stability, fish.

Advances in Aquaculture and Fisheries Management Vol. 2 (6), pp. 162-170, June, 2014. © International Scholars Journals

Full Length Research Paper

Current transformations in fish communities of the equatorial Lake Naivasha, Kenya

Amobi Musyoka, Bochabery O. and Brayant Ajwang

Department of Fish economics and management, Faculty of Agriculture, University of Nairobi, Nairobi, Kenya. E-mail: [email protected]

Accepted 25 May, 2014

Abstract 

Changes in fish species composition and abundance in Lake Naivasha were investigated monthly for a period of 12 months. Data were obtained both from experimental surveys as well as commercial fish landings. The structure metrics considered included species abundance and composition, length-frequency and physico-chemical attributes. Results of the study showed that the fishery is currently dominated by the recently introduced common carp, Cyprinus carpio accounting for over 95% of the total fish landings, with the naturalized fish populations performing dismally both in terms of abundance as well as health conditions. The entry of the common carp into Lake Naivasha may have completely transformed the lake’s ecosystem integrity, driving the initially abundant tilapiine species to near local extinction. The study also confirms a restricted distribution of Micropterus salmoides to rocky-bottomed habitats of Hippo Point and Crescent Lake. Conversely, the long-fin barb, Barbus paludinosus, initially confined to the north swamp and the mouth of River Malewa, currently exhibits a lake-wide distribution. The changing climatic conditions as manifested in the lake level recessions may be a real threat to the fish stocks in the lake. Human activities in the catchment areas may also have contributed to the recent ecological changes witnessed in Lake Naivasha. This study proposes a number of recommendations with a view to ensuring ecosystem integrity and consequent sustainable fisheries of Lake Naivasha.

Key words: Ecosystem integrity, habitat preference, species introductions, sustainable fisheries, fish population, equatorial lake.

Advances in Aquaculture and Fisheries Management Vol. 2 (6), pp. 157-161, June, 2014. © International Scholars Journals

Full Length Research Paper

Assessment of Some weighty metals and polycyclic aromatic hydrocarbons roasted food in Amassoma, Niger Delta, Nigeria

Ojih Samson, Bello Edeh and Adeyeye Gbagi

Chemistry Advance Laboratory, Sheda Science and Technology Complex, P. M. B. 186, Garki, Abuja FCT, Nigeria. E-mail: [email protected]

Accepted 06 May, 2014

Abstract 

Analysis of raw and roasted ready-to-eat foods namely; Atlantic mackerel (Scomber scombrus), suya beef and plantain (Musa paradiasca) sold and consumed in Amassoma town were screened for the presence of 15 polycyclic aromatic hydrocarbons (PAHs). Concentration of chromium, lead and cadmium were also determined after digestion with aqua regia and analysed using atomic absorption spectrophotometer. Column chromatography, packed with anhydrous Na₂SO ₄ and silica gel was used for PAH extraction with dichloromethane as the eluting solvent. The identification and concentration of PAHs were carried out by gas chromatography GC/FID with the aid of 15 PAH standards. Appreciable amount of benzo[a]pyrene (2.41 µg/g) and benzo[b]fluoranthene (4.51 µg/g) were found present in roasted mackerel fish; while a mean of 7.23 µg/g of benzo[a]anthracene was detected in suya beef. Thirteen (13) other PAHs were present at various concentrations in the smoked fish. No PAH was detected in roasted plantain and in the raw food items. Levels of the heavy metals were found in trace amounts and were below World Health Organization limits for human consumption.

Key words: Gas chromatography, benzo[a]pyrene, chromium, lead, smoked fish, suya plantain.