M. EGWENOMHE

The quality of meat is affected by the nutrition of the fish. Recently, most Tilapia farmers have developed the habit of feeding fish with Lemna minor in order to reduce the quantity of feed used to rear fish. This study investigated the effect of Lemna minor (duckweed) supplementation in culture water on the proximate and mineral composition of Oreochromis niloticus (Nile tilapia). Fingerlings were cultured for 12 weeks in a completely randomized design with four treatments: T0 (control, commercial feed only), T1 (1/2 commercial feed fed in T0 + duckweed), T2 (same quantity of commercial feed fed in T0 + duckweed), and T3 (duckweed only). Each treatment was replicated three times, with 50 fish per 2000 L tank. Fish were harvested at the end of the 12 weeks culture period, filleted, and analyzed for proximate composition (moisture, protein, fat, ash, crude fibre, and carbohydrate) and mineral content (Ca, P, Mg, Na, K, Fe, Zn) using standard AOAC and ISO procedures. The results of the study showed significant difference (P<0.05) across all proximate and mineral parameters. Moisture (77.86±0.06%) and carbohydrate (0.96±0.02%) were highest in T3, while crude protein (18.99±0.04%) and fat (6.36±0.04%) were highest in T1. Ash and fibre were moderately increased in duckweed treated groups. Mineral analysis revealed the highest concentrations in T3 for Ca (3.2065±0.0053 mg/g), P (9.8102±0.0053 mg/g), Mg (1.1670±0.0036 mg/g), K (3.1050±0.0055 mg/g), Na (0.8926±0.0047 mg/g), Fe (0.0338±0.00008 mg/g), and Zn (0.0232±0.00004 mg/g) The results demonstrate that Lemna minor serves as a natural bioenhancer, improving the nutritional and mineral quality of O. niloticus through nutrient recycling and water enrichment. The integration of duckweed into aquaculture systems presents a sustainable, cost effective, and eco-friendly strategy to enhance fish growth, flesh quality, and overall nutritional value for consumers.

The abundance of duckweeds in earthen fish ponds is a phenomenon that warrants detailed study due to its ecological, economic, and management implications. This study investigated the abundance, spatial distribution, and management of Lemna minor (duckweed) in earthen fish ponds along the Ikpoba River in Benin City, Edo State, focusing on Oredo and Ikpoba-Okha Local Government Areas. Structured questionnaires and field assessment were used to collect
data from 100 fish farmers, while descriptive and spatial analyses were performed to evaluate duckweed coverage, biomass, and management practices. Results showed that Lemna minor was relatively abundant, with mean coverage of 63.8% (40.8 g/m²) in Oredo and 66.2% (42.9 g/m²) in Ikpoba-Okha, particularly concentrated at pond inlets where nutrient inflow was greatest. Most farmers were educated (54.2%) males aged 30–39 years (56%), mainly culturing Clarias
gariepinus (60.2%) under intensive systems. About 63.2% of respondents reported duckweed presence, primarily during the rainy season (86.6%), with 28.3% perceiving it as beneficial for water shading and nutrient removal, while 17.2% considered it harmful due to oxygen depletion and feeding obstruction. Manual removal (54.3%) and biological control (21.7%) were the most common management practices, though only moderately effective. It concludes that L. minor
proliferation indicates nutrient-rich pond conditions and recommends integrated management through nutrient regulation, regular monitoring, and biological control to enhance sustainable aquaculture productivity

Fish seed production is a fundamental aspect of aquaculture, ensuring the continuous supply of high-quality fish seeds for commercial and subsistence fish farming. This study examined the fish seed production practices in Ovia North-East and Ovia South-West local government areas of Edo State, Nigeria. The objectives were to assess the socio-economic characteristics of fish seed producers, evaluate their management practices, analyze production output, and identify constraints affecting fish production in the study area. The non-probability chain referral sampling procedure was employed, with data collected from 100 fish hatchery operators using structured questionnaires. The collected data were analyzed using S.P.S.S Version 15.0, and presented using descriptive statistics, including tables, charts, and percentages. The findings revealed that fish seed production is largely undertaken by middle-aged (51.9%), experienced (40.5%), and predominantly male operators (94.9%). Also, Clarias gariepinus and Heterobranchus bidorsalis (97.5%) were predominant species bred in hatcheries. Water quality management was a key concern, as many operators relied on basic flow-through systems (73.2%) and oxygenation methods (25.6%) to maintain optimal conditions. Broodstock reuse was common, with most operators (89.7%) allowing a recovery period of 3 – 4 months before reuse. The study identified poor water quality leading to fry mortality (55.7%), financial constraints (27.9%), feed availability and cost (13.9%), and theft (2.5%) as the major challenges faced by hatchery operators. Based on the findings, the study recommends enhanced training programs, targeted funding schemes, better water quality management strategies, and security measures to enhance efficiency and overall productivity of fish seeds in the study area. Also, further studies should be carried out on other aspects of the fish seed production value chain to enable a comprehensive understanding of the fish seed production in the study area.