The development of antibiotic-resistant pathogens due to the indiscriminate use of antibiotics has led to advocacy for the use of natural products in the treatment of fishdiseases. The antimicrobial activity of methanolic and ethanolic extracts of walnut leaves and onion bulbs were evaluated against six pathogenic bacteria (Pseudomonas aeruginosa, Staphyloccocus aureus, Bacillus subtilis, Pseudomonas fluorescens,Escherichia coli, Samonella typhi) using the cup – plate method. Minimum Inhibitory Concentration (MIC) was determined using standard methods. Data were analysed using descriptive statistics. Onion bulbs and walnut leaves were also screened for secondary metabolites and this indicated the presence of saponins, tannin, alkaloids, cyanogenic glycosides and flavonoids; while anthraquinones were not detected in both plants. The zone of inhibition varied with the bacteria and type of extract. The average diameter of inhibition zones was 10 ± 0.00 and 9 ± 0.02 mm for methanolic and ethanolic extracts of walnut leaves and onion bulbs, respectively. Staphylococcus aureus, B. subtilis and P. aeruginosa were most sensitive to the extracts. However, S. aureus was more sensitive to the extracts of walnut leaves and S. typhi was the least sensitive. Bacillus subtilis wasmore sensitive to the extracts of onion compared to E. coli which was the least sensitive. Minimum inhibitory concentration of walnut leaves and onion bulbs extracts on the bacteria tested were both 500 µg/ml. The results indicated that walnut leaves and onion bulbs had antibacterial activity on the tested organisms and showed their prospects for their use in the treatment of fish diseases. Key words: Antibacterial activity, onion bulb extract, walnut leaf extract, fish diseases.

In this study, the potential benefits of ten edible leaves (Manihot esculents, cassava leaf; Colocasia esculenta, cocoyam leaf; Talinum triagulare, water leaf; Telfairia occidentalis, fluted pumpkin leaf; Carica papaya, pawpaw leaf; Amaranthus chlorostachys, green leaf; Moringa oleifare, drumstick leaf; Vernonia amygdalina, bitter leaf; Ipomoea batatas, sweet potato leaf and Basella alba, Malabar spinach ‘Amunututu’ to aquatic animal nutrition and health were studied along with proximate, mineral and phytochemical compositions. Results show that theses edible leaves were a good source of protein and the highest crude protein was obtained in C. papaya (32.6%) while the lowest in C. esculenta (14.7%). The highest and lowest total ash was found in T. triagulare (34.6%) and C. papaya (11%) respectively. The result showed that the edible leaves are rich in wide variety of secondary metabolites of phytochemical constituents such as tannins, alkaloids, flavonoids, saponins, glycosides oxalates and phytate which can act against different diseases. Results suggest that inclusion of edible leaves may be nutritionally beneficial and this could promote growth, immune system and enhance disease resistance properties and subsequently very potential to reduce the cost of highly priced supplementary feeds.

The Potential of Different Extraction Methods of Soursop ( Annona Muricata Linn) Leaves as Antimicrobial Agents for Aquatic Animals