African Journal of Fisheries and Aquatic Resources Management

Bacteriological Examination of Tilapia (Oreochromis niloticus) in Makoko Market in Lagos, Nigeria

2021-03-30T09:41:40+00:00

Abstract Bacteriological examination was conducted on forty fresh tilapia (Oreochromis niloticus)selected randomly from a market in Lagos using standard microbiological methods.The fish was carefully weighed and measured.Of the 40 fish, 16 ( 40%)weighed between 51and100 g, 12 (30%)weighed between 201and 250 g, while 4 (10%) weighed 1-50 g, 101-150 and 201-250 g respectively. Twenty(50%)ofthefishhadlengthsrangingfrom11-15cm,12(30%)within21-25cmand8(20%) within 16-20 cm length while none of the fish was less than 10 cm in length.A total of 188 isolates which belong to seven different bacterial species were recovered from the gills and intestines of the tilapia. Escherichia coli constituted 48 (25.5%), Proteusspp., 36 (19.2%), Klebsiella spp., 32 (17%), Pseudomonas spp., 20 (10.6%), Enterobacter spp., 18(9.6%), Coagulase-negative Staphylococci (CONS) 18 (9.6%), while Staphylococcus aureus 16 (8.5%) was the least.The bacterial isolates were evenly distributed in the gills 92 (48.9%) and intestines, 96 (51.1%). Similar bacteria were isolated from the gills and intestines of the fish. The bacteria showed high susceptibility to all the antibiotics tested, thus are not likely to pose a public health threat

Cytogenotoxicity Effects of Some Selected Heavy Metals on Oreochromis niloticus and Clarias gariepinus

2021-03-30T09:19:22+00:00

Abstract

The contamination of natural waters by heavy metals depreciates aquatic biota and poses considerable environmental risks and concerns. This study investigated the cytogenetic abnormalities associated to Oreochromis niloticus and Clarias gariepinus exposed to some selected heavy metals [Mercury (Hg), Zinc (Zn), Lead (Pb) and Nickel (Ni)] using micronucleus (MN) and nuclear abnormalities (NA) tests in peripheral erythrocytes. Acute toxicity bioassay was conducted in a semi static system to determine the 96-h LC50 value of the test chemicals following standard methods. The sublethal doses for all the heavy metals used were calculated as 75% of the obtained LC [Sub Lethal dose 3 (SL3)]. Fishes were exposed to SL3 for 21 days 50 after which they were harvested and the cytogenetic toxicity endpoint assessed. The NAshapes were scored into binucleated cells, micronucleated, notched, blebbed, vacuolated, dumb-bell shaped and deshaped nuclei. Result of acute toxicity showed that lethality increased with increase in heavy metal concentration. It was observed that, fish species showed significant sensitivity to the different heavymetalstreatment.In general,the highest value of bothMNandNA cells were significantly increased in the exposure and followed trend as Hg > Pb ?Zn ?Ni. On the other hand, C. gariepinus was more sensitive to the three heavy metals exposure than O. niloticus. The frequencies of each NAshape were found in all the fish species and in all the treatments as follows NT>LB>BN>BL. Results showed that the exposed fishes showed cytogenetic alterations in their genetic materials. Heavy metals in natural water body can be bio accumulated and biomagnified in fish and consumption of such fish contaminated with metals thus poses a risk to human health.

Efficiency and Selectivity of Monofilament Gillnet for Three Commercially Important Cichlids Species in Erelu Reservoir, Oyo, Nigeria

2021-03-30T07:08:53+00:00

Abstract

Gillnet selectivity is crucial for the effective and sustainable management of fisheries. However, there is a knowledge gap on gillnet selectivity for commercially important Tilapia species in EreluReservoir.Thisstudyestimated the selectivity parameters of commonly used monofilament gillnets for three commercially important cichlid species in Erelu Reservoi The reservoir was divided into upper, middle and lower zones based on geographical location Fleet of monofilament gill nets mesh sizes: 38.1, 50.8, 63.5, 76.2, 88.9, 101.6 and 127.0 mm were randomly set in each zone on a monthly basis for 21 months covering two wet and dry seasons, respectively. The catches were identified, counted and efficiency of each gillnet estimated for Oreochromis niloticus, Sarotherodon galileaus and Pelmatolapia mariae by calculating the catch-per-unit effort. The selectivity parameters such as Selection Factor (SF) and Selection Variance (SV) for each combined gillnets were determined from regression analysis while the Common Length of Selection (CLS) and optimum selection length were obtained from selectivity curve. The size at first maturity of the cichlids were determined using length frequency analysis wizard. Highest and least catch per unit effort for Oreochromis niloticus (76.2mm;127.0mm), Sarotherodon galileaus (76.2mm;127.0mm) and Pelmatolapia mariae (63.5mm;38.1mm) were 13.57g/m;0.20g/m,8.29g/m;0.10g/mand4.65g/m;0.40g/m,respectively.TheSF,CLSandSVfor the combined gillnet 76.2mm/63.5mm were 0.21;17.5cm; 2.91 and 0.19; 16.5cm and 1.86 for Oreochromis niloticus and Pelmatolapia mariae, respectively. The optimum selection length of 18.83cm (Oreochromis niloticus), 19.04cm (Sarotherodon galileaus) and 17.12cm (Pelmatolapia mariae), respectively were recorded for 76.2mm gillnet. Considering the size at first maturity of 17.9± 0.6cm, 16.5±0.2 and 15.0±0.3cm for Oreochromis niloticus, Sarotherodon galileaus and Pelmatolapia marie, respectively mesh size of 76.2mm will be appropriate for sustainable exploitation of these tilapia spp.in Erelu Reservoir

Use of Agro-Industrial Waste (Brewer's Dried Grain) to Substitute Maize in the Diet of African Catfish Clarias gariepinus

2021-03-30T09:45:11+00:00

Abstract

This study was carried out to assess the nutrient utilization and growth response of juvenile catfish fed diet with maize replaced with agroindustrial waste. One hundred and fifty Clarias gariepinus juvenile (5.21±0.14g) were randomly assigned to five diets formulated such that brewery waste replaced maize at 0%, 10%, 20%, 30%, and 40%, respectively and fed at 5% body weight. Evaluation of nutrient utilization and growth parameters of the experimental fish followed standard methods as based on feed intake, weight gain, feed conversion ratio, specific growth rate, relative growth rate, daily weight gain, gross feed conversion efficiency, protein efficiency ratio and evaluation of the economic cost. The result showed that there was no significant difference (p>0.05) in the weight gain of the fish among treatments. Control (0%) diet had the highest mean weight gain of 9.69g while the least weight gain was obtained from 20% dietary treatment which recorded a value of 7.40g. This experiment revealed that brewer's dried grain can be tolerated by C. gariepinusjuveniles, there was weight gain at 40% growth rate. Feed intake was affected by the brewer's waste that replaced maize and fish performed well even at the highest level of replacement (40%). The lowest cost for the production of a kg weight gain was from the treatment with replaced maize grain with 40%. Considering the performances of the experimental fish and the cost per kg weight gain, it is advantageous to use brewer's waste as an additional feed in the feed mix or a sole supplementary feed. The study has shown that agroindustrial by-product can replace maize in the diet of Clarias gariepinus.

Gender Roles and Poverty Determinants of Fish Farmers’ Households in Oyo State, Nigeria

2021-03-30T09:28:41+00:00

Abstract

Aquaculture can be a key engine of growth and poverty reduction in Nigeria. The sector is however underperforming partly because women who are often a crucial resource face constraints that reduce their productivity. Their non-defined roles vary considerably and are changing rapidly leading to greater depth of poverty as economic and social forces transform the aquaculture sector. This study examined gender roles and poverty determinants of fish farmers’households in Oyo State.Amultistage sampling technique was used to select 250 respondents using well-structured questionnaires based on the fourAgricultural Development Programme zoning in Oyo State. Descriptive statistics, t test, Chi square, Harvard gender analysis framework, Foster Greer and Thorbecke poverty measure (FGT) and Probit models were used to analyse the data at á0.05 Result showed that 64.4% of the fish farmers were males, with mean age of 46.27±9.38 years and 55.3% had tertiary education while 35.6% were females with mean age of 41.43±10.42. 55.1% had tertiary education. However, 89.2% had male as household head with mean age 46.56±9.18 while female headed household only 10.8% with mean age of 47.63±14.5. Nineteen fish farming activities were considered and both gender were involved in all. In 15 activities there were significant differences in participation of the roles performed while there was no significant difference in only four roles. FGT for male showed that 70.81% were poor while 29.19% were nonpoor. Poverty index was (0.2919), Poverty depth (0.1673) and poverty severity was (0.1159) while for the female, 74.16% were poor and 25.84 were non-poor. Poverty index was (0.2584), Poverty depth (0.1352) and Poverty severity was (0.0889). There was significant difference between the poor and non-poor in both gender. The result of Probit regression for male indicated that farm size and household size, were the major determinants of poverty in the study area while marital status (married), education (No education and tertiary), household size and fish farming experience were the determinant of poverty for females in the study area. Larger farm size for males and higher educational level for females should be encouraged among the fish farmers to help improve their output and make them less susceptible to poverty as well as to be food and nutrition secure.

Effects of Varying Levels of Ocimum gratissimum Leaf Powder on Growth Performance and Feed Utilization of Heterobranchus bidorsalis Fingerlings

2021-03-30T08:33:10+00:00

Abstract
Growth performance and feed utilization of Heterobranchus bidorsalis fingerlings fed
varying inclusion levels of diets supplemented with Ocimum gratissimum leaf powder were
assessed in the study. Apparently healthy H. bidorsalis fingerlings (12.05g ± 0.01) were
randomly divided into five treatment groups representing iso-nitrogenous diets (about 40%
crude protein) containing varying inclusion levels 0g/100g (control), 0.5g/100g, 1.0g/100g,
1.5g/100g, and 2.0g/100g of O. gratissimum leaves denoted as CTR, OG1, OG2, OG3 and
OG4 respectively. The fish were fed these diets for 70 days in triplicate. The experimental
fish were randomly distributed into fifteen plastic tanks of dimension 40 ×30×35cm3 at a
stocking density often fish pertank.Heterobranchus bidorsalisfingerlingsfed 1.5g/100g diet of
O. gratissimum recorded the best growth performance in terms of body weight gain, feed
conversion ratio (FCR) and specific growth rate (SGR). There was a significant increase in
growth and nutritional performance of H. bidorsalis fingerlings with increasing inclusion of O.
4 3 2
gratissimum leaves (P<0.05). A differential equation (y = -15.227x + 53.533x - 54.453x +
17.887x + 22.07; R² = 1) showed that highest weight gain occurred at O. gratissimum level of
approximately 1.65 g/100g. The study therefore showed that O. gratissimum leaves as an additive
significantlyimprovedgrowth and feed utilizationparametersinthe treatedgroups.Abstract
Growth performance and feed utilization of Heterobranchus bidorsalis fingerlings fed
varying inclusion levels of diets supplemented with Ocimum gratissimum leaf powder were
assessed in the study. Apparently healthy H. bidorsalis fingerlings (12.05g ± 0.01) were
randomly divided into five treatment groups representing iso-nitrogenous diets (about 40%
crude protein) containing varying inclusion levels 0g/100g (control), 0.5g/100g, 1.0g/100g,
1.5g/100g, and 2.0g/100g of O. gratissimum leaves denoted as CTR, OG1, OG2, OG3 and
OG4 respectively. The fish were fed these diets for 70 days in triplicate. The experimental
fish were randomly distributed into fifteen plastic tanks of dimension 40 ×30×35cm3 at a
stocking density often fish pertank.Heterobranchus bidorsalisfingerlingsfed 1.5g/100g diet of
O. gratissimum recorded the best growth performance in terms of body weight gain, feed
conversion ratio (FCR) and specific growth rate (SGR). There was a significant increase in
growth and nutritional performance of H. bidorsalis fingerlings with increasing inclusion of O.
4 3 2
gratissimum leaves (P<0.05). A differential equation (y = -15.227x + 53.533x - 54.453x +
17.887x + 22.07; R² = 1) showed that highest weight gain occurred at O. gratissimum level of
approximately 1.65 g/100g. The study therefore showed that O. gratissimum leaves as an additive
significantly improved growth and feed utilization parameters in the treated groups.

Evaluation of Tribulus terrestris Powdered Seed as Androgenic Agent for Production of All Male Red-Belly Tilapia, Coptodon zillii (Gervais 1848)

2021-03-29T21:27:09+00:00

Abstract

The study investigated the effect of dietary doses of Tribulus terrestris on the sex reversal and production of Coptodon zillii fry. A total of two hundred and seventy (270) three days old apparent healthy fry of C. zillii (mean weight 0.03 ± 0.0g) were randomly selected and distributed 3 into 18 glass tanks (70x45x45 cm ) at 15 fish per tank representing five treatments in triplicate to contain T. terrestris at different inclusion levels of 0.00 (negative control), 10.0, 15.0, 20.0 and 25.0g/kg T. terrestris seeds powder basal diet and labelled (T1-T5). Areference diet contain 0.06 g/kg of basal diet of 17á methyltestosterone (MT) was also formulated as positive control and labelled (T6). At the end of the experiment, final growth weights were recorded and the carcass composition determined. Gonad squashing method involving aceto-carmine staining was used to determine the sex of the fish. Results indicated that dietary treatment with powdered T. terrestris seeds and MT at different concentrations showed no significant difference (P>0.05) in survival percentage compared to that in control group, and growth parameters were better in fish fed T. terrestris and MT treated groups than in the fish fed T1. The highest weight gain was recorded in fish in T4 while the least value was observed in fish fed control diet. All fish fed diet containing T. terrestris and MT treated groups had significantly higher male proportion than untreated group (36.2%). The percentage of male (78.5%) population in T. terrestristreatments in this study was significantly lower than MTtreated group (92.1%) and significantly higher than untreated group. Carcass protein decreased with increasing levels of T. terrestris in the diet. The study indicated that T. terrestris seed powder might be used as a potential alternative to synthetic steroid for production of all male tilapia population.

Bacteriological Analysis of Mullet (Mugil cephalus) in Makoko, Lagos, Nigeria

2021-03-30T09:52:06+00:00

Abstract

Atotal of 60 fresh Mugil cephalussamples were bought from Makoko market in Lagos and were analysed bacteriologically. Cultures of the gills and intestinal tissues of the 60 fish were made on selective media using standard microbiological methods. The weights and sizes of the fish were measured using Mettler's balance and a ruler. Antibiotics susceptibility patterns of the isolates were carried out using disc diffusion technique. Majority, 30 (50%) of the fish studied weighed between 51 and 100g, 18(45%), weighed between 201 and 250g, while 6(15%) weighed between 101 and 200g. The sizes of the fish were 24(40%) within 16 and 20cm, 24(40%) were between 21 and 25cm, while 12(20%) were within 21and 25cm range in length. A total of 312 bacterial isolates which belong to six different bacterial species were recovered from the fish. One hundred and sixty two (52%) were recovered from the intestine, while 150 (48%) were isolated from the gills. Klebsiella spp was the most recovered with 108 (34.6%), Enterobacter spp. 60(19.2%),Proteusspp. 48(15.4%), Escherichia coli, 36 (11.5%) while both Staphylococcus aureus and coagulase negative Staphylococci had 30 (9.6%) each, being the least isolated. E coli was only recovered from the intestine while none was isolated from the gills. The bacterial isolates showed a high susceptibility to the antibiotics tested, thereby suggesting that the bacteria may not have been exposed to such drugs.

Growth and Economic Performances of African Catfish, Clarias gariepinus Reared under Different Culture Facilities

2021-03-30T09:33:38+00:00

Abstract

This study determined the growth and economic performances of African Catfish, Clarias gariepinus reared in plastic tanks, sandcrete tanks and earthen ponds for 185 days. Nine hundred C. gariepinus fingerlings (mean weight 7.38 ± 0.02g) were acclimatized for 24 hours, out of which one hundred fingerlings were randomly selected and distributed into the three prepared culture facilities (plastic tanks, sandcrete tanks and earthen ponds) of the same size (3.0m X 2.8m X 1.0m), labelled as T1, T2 and T3 respectively. Each treatment was in triplicates; the culture facilities were filled with water up to 3/4 in all the treatment. The fingerlings were fed with formulated standard diet of 40% crude protein at 5% body weight. Fish were fed twice daily at 09:00 and 16:00 hours for 185 days. At final harvest, the total yield of fish was significantly greater (P<0.05) in earthen pond, 3.8kg than those in sandcrete tank, 2.4kg and plastic tank 2.12kg. There were significant differences (P<0.05) in final weight gain, feed conversion ratio, mean daily weight gain between C. gariepinusfingerlings stocked in plastic tank, sandcrete tank and earthen pond. Fish in earthen pond had the highest weight gain (1061.2g), specific growth rate (2.68%) than sandcrete tank (835.9g, 2.56%) and plastic tank (772.9g, 2.52%), while survival percentage of C. gariepinusfrom plastic tanks, sandcrete tanks and earthen ponds were: 90.00%, 87.3% and 76.7% respectively. Net profit obtained was N26,072 (earthen pond), 19,294.67 (sandcrete tank) and 18,286.67 (plastic tank). The benefit cost ratio was higher in earthen pond (2.130) than the sandcrete tank (1.773) and plastic tank (1.763). The study considered earthen pond enclosure system to be more productive and the most ideal culture facility for growth optimization in C. gariepinus.

Growth Performance and Nutrient Utilization of African Catfish Fed Yeast Fermented Shrimp Head Meal in Replacement for Fish Meal

2021-03-30T08:37:06+00:00

Abstract

Yeast fermented shrimp head meal was used to replace the more expensive fish meal (FM) to reduce costs of production and improve the profit margin. Shrimp head waste was fermented with yeast for 24 hours and used to replace FM at 0, 10, 20, 30 and 40% making up five treatments The diets were fed to fingerlings of C. gariepinus (5.61±0.04g) to apparent satiation for 70 days. The results showed that the growth performance of fish fed diet of 100% fish meal and the groups fed diets containing 10%, 20%, 30% fermented shrimp head waste meal was not statistically significant (P>0.05) with 30% replacement level having the best performance. The growth performance showed a declining trend with the fish fed diet containing 40% of the shrimp head meal. However, replacement of fish meal with the shrimp head waste meal did not affect the blood profile (P>0.05) of the fish. Differences in the carcass amino acid levels were marginal indicating that physiological functions might not have been compromised. In conclusion, yeast fermented shrimp head meal can replace up to 30% of FM in the diets of African catfish while the optimal level of replacement is 20% as indicated by the regression analysis.

Effect of Season on Genotoxicity and Heavy Metal Accumulation in Oreochromis niloticus and Clarias gariepinus from the Lower River Niger, Nigeria

2021-03-29T21:34:51+00:00

Abstract

The level of heavy metal concentration and genotoxicity was assessed in both Oreochromis niloticus and Clarias gariepinusfrom the Niger River, Nigeria. Fish samples were collected both during the dry and wet season between April, 2017 and September, 2018. Aluminium (Al), Chromium (Cr), Copper (Cu), Iron (Fe), Nickel (Ni), Zinc (Zn), Mercury (Hg), Arsenic (As), and Lead (Pb) concentrations in fish samples were also analysed using Inductively Coupled Plasma Optical Emission Spectrometroscopy (ICP-OES). Result showed higher accumulation of heavy metals in both fish tissues in the wet season than the dry season. The highest accumulated heavy metal in the fish sample was Fe during the dry seasons [(Fe (O. niloticus) = 64.28±12.93 mg/g, Fe (C. gariepinus)]= 96.06±58.36 mg/g) and wet season [Fe(O. niloticus) = 67.42±14.11 mg/g, Fe (C. gariepinus)] = 99.16±59.36 mg/g). Heavy metal accumulation evaluated followed the trend Fe > Al > Cd > Zn > Pb > Cu > As > Ni > Cr > Hg for the dry season and Fe > Al > Zn > Cu > Pb > Cr > Ni > Cd > As > Hg for the wet season in O. niloticus; and Fe > Al > Zn > Pb > Cu > Cr > Ni > Cd > As > Hg for the dry season and Fe > Al > Zn > Pb > Cu > Ni > Cr > Cd > Hg > As for the wet season in C. gariepinus. Most of these heavy metals were beyond international permissible limits. The four polymorphic RAPD markers used in the study showed more polymorphisms in C. gariepinusthan O. niloticusin both the dry and wet season. There was no difference in the polymorphic bands between dry and wet season in O. niloticus while more polymorphic bands were observed in wet season (50 bands) than dry season (47 bands) tissues of C. gariepinus. The result indicated a lower Genomic template stability (GST) in C. gariepinus (dry = 2.70, wet = 5.41) than O. niloticus (dry = 13.16, wet = 13.16) when compared in both seasons. This study revealed the level of toxic metal accumulation and genotoxic potentials of these fishes in the food chain of locals consuming them. Drastic measures are of high necessity in order to protect both the aquatics and potential consumers in the area.