Project : USDA ARS

ARS Home » Southeast Area » Stoneville, Mississippi » Warmwater Aquaculture Research Unit » Research » Research Project #447537

Research Project: Maximizing Profitability and Fish Health in Catfish Aquaculture

Location: Warmwater Aquaculture Research Unit

2025 Annual Report

Objectives
Objective 1. Optimize fingerling and food fish productivity to maximize economic returns. Objective 2. Optimize catfish diets for efficient growth and economic returns. Subjective 2.1. Evaluate alternative protein ingredients for channel and hybrid catfish. Sub-objective 2.2. Evaluate the supplementation of soy lecithin to catfish fingerling diets. Sub-objective 2.3. Evaluating feed additives on production and health. Objective 3: Identify and characterize existing and emerging Flavobacterium, Edwardsiella, Aeromonas spp. and other pathogens from catfish aquaculture. Sub-objective 3.1. Diagnostics and pathology support identifying priority fish health issues. Sub-objective 3.2. Development of molecular diagnostic tests to speciate and identify strain variation of parasitic and bacterial pathogens. Sub-objective 3.3. Characterization of yellow-pigmented bacteria. Sub-objective 3.4. Epidemiology of myxozoan dynamics in hybrid and channel catfish production ponds. Objective 4: Develop and optimize vaccines, vaccine delivery strategies and other approaches for managing catfish health. Sub-objective 4.1.1 Develop a bivalent vaccine to protect catfish against Edwardsiella spp. Infections. Sub-objective 4.1.2 Assessing the need for revaccinating fish during the second year of production following winter warehousing of stocker catfish. Sub-objective 4.1.3. Efficacy of vaccination at temperatures below the threshold permissive for E. ictaluri infection. Subobjective 4.2. Control of Parasitic Infections in commercially raised catfish. Subobjective 4.2.1 Using copper sulfate to control snails serving as disease vectors of trematode infections. Subobjective 4.2.2 Evaluating snail baits to control snail disease vectors. Subobjective 4.2.3. Develop Experimental Baits with Activity against Snails. Sub-objective. 4.3 Assessment of anti-parasitic agents to break the H. ictaluri life cycle.

Approach
The catfish industry is the largest sector of United States aquaculture with economic contributions of over $2.0 billion annually. The industry is particularly prominent in Alabama, Arkansas, Mississippi, and Texas, which collectively contribute to 96% of the nation's catfish production. Mississippi alone accounts for over half of the total production area and volume. Despite its historical success, the domestic catfish aquaculture sector has faced considerable challenges, including a notable threefold reduction in acreage over the past two decades. This downturn is attributed to several factors, including increased losses due to disease, rising production costs, and competition from more affordable imports, which often originate from regions with substandard regulatory oversight. Feed expenses, which comprise over 50% of total production costs, have escalated, underscoring the urgent need for identifying alternative feed ingredients and implementing cost-effective formulations to sustain profitability. Although the shift towards intensive production systems and the introduction of hybrid catfish varieties have resulted in a threefold increase in yield, profitability remains a concern for producers. The intensification associated with hybrid catfish farming has led to the emergence of diseases previously rare in channel catfish, thereby diminishing yields and economic returns despite initial gains in survival and growth. To address these challenges, research efforts are crucial to developing lower-cost diets using alternative feed ingredients and establishing functional feeds using feed additives to enhance digestibility and fish health. Additionally, there is a need for research aimed at devising profitable management strategies for hybrid and channel catfish, encompassing production methods and disease management approaches to mitigate the economic impact of infectious diseases. The proposed research is crucial for ensuring the continued viability of the catfish aquaculture industry in the United States, amid persistent challenges and evolving market conditions. It aims to foster the development of a sustainable and wholesome seafood supply, underpinning the sector's future success and resilience.

Progress Report
Under Objective 1, optimize Fingerling and Foodfish Productivity to Maximize Economic Returns This objective focuses on pond renovations and the reconfiguration of aerators to evaluate the effect of aeration horsepower on production yield. Ponds have been drained in preparation for renovation; however, anticipated state funding for FY2025 was denied. The current lack of funding will delay all studies associated with this objective. Under Objective 2, optimize Catfish Diets for Efficient Growth and Economic Returns Subobjective 2.1: Laboratory studies evaluating diets formulated by replacing soybean meal, cottonseed meal, and fish meal with alternative protein sources have been initiated. Results will be reported in next year’s annual report. Subobjective 2.2: Laboratory studies evaluating soy lecithin supplements in catfish fingerling diets have been initiated. Results will be reported in next year’s annual report. Subobjective 2.3: Experiments evaluating feed additives for their effects on fish production and health, including screening of potential antimicrobials, have been initiated. Results will be reported in next year’s annual report. Under Objective 3, identify and Characterize Existing and Emerging Pathogens (Flavobacterium, Edwardsiella, Aeromonas spp., and Others) in Catfish Aquaculture Subobjective 3.1: Diagnostic cases from the 2025 production season are currently being processed and recorded. A year-end diagnostic report will be available in 2026. Subobjective 3.2: Molecular diagnostic tests to identify species and strain variation among Streptococcus isolates have been initiated. These results will support epidemiological studies and vaccine development. Results will be reported in next year’s annual report. Subobjective 3.3: Yellow-pigmented bacteria collected from 2025 diagnostic submissions have been transferred to collaborators for genomic sequencing. Additional isolates collected during the 2025 production season will be treated similarly. Results will be reported in next year’s annual report. Subobjective 3.4: Proliferative Gill Disease (PGD) is most problematic during early spring. A study evaluating the epidemiology of myxozoan infestations in hybrid and channel catfish will begin in spring 2026, representing Month 12 of the project. Under Objective 4, develop and Optimize Vaccines and Vaccine Delivery Strategies for Managing Catfish Health Subobjective 4.1: Edwardsiella piscicida isolates have been serially passaged on antibiotic media to develop attenuated strains. These isolates will be evaluated for safety and efficacy in laboratory trials. Results will be reported in next year’s annual report. Subobjective 4.2.1: Fish have been vaccinated and are being maintained in tanks supplied with surface water. Vaccinated and non-vaccinated fish will be held through the winter. A challenge trial with E. ictaluri will be conducted when pond temperatures become permissive in spring 2026. Subobjective 4.2.2: Evaluation of vaccine efficacy at low temperatures is scheduled to begin in Month 36 of the project. Under Objective 5, control of Parasitic Infections in Commercially Raised Catfish Subobjective 5.1: Initial studies using granular copper sulfate applied with a prototype delivery system were effective in minimizing snail populations in experimental ponds. Modifications are being made to finalize the delivery system, which will be used in commercial field trials in spring 2026. Subobjective 5.2: The use of commercially available snail baits is currently being evaluated in laboratory settings. Trials are expected to be completed by the end of FY2025. Subobjective 5.3: Ingredients for the development of experimental snail baits have been acquired and used to assess pellet stability in water. Formal stability trials have not yet been conducted. Molluscicidal compounds will be incorporated once a stable formulation is identified. Results will be reported in next year’s annual report. Subobjective 5.4: Antiparasitic agents are currently being evaluated in fish infected with myxozoan species. In addition, praziquantel is being assessed in fish infected with trematodes. These studies are ongoing, and results will be reported in next year’s annual report.

Accomplishments

U.S. DEPARTMENT OF AGRICULTURE

Warmwater Aquaculture Research Unit: Stoneville, MS