Published in PLOS One on 2026-05-20, this study is presented as an attributed evidence briefing. The excerpts below are the original researchers’ words, reproduced under their Creative Commons Attribution licence. Health Signal has selected the abstract and, where needed, opening background paragraphs; the complete methods, results, limitations and references remain in the linked paper.
Original authors: Nader Iskandar Hamwi, Hamam Adib Altajer
Source: PLOS One • DOI 10.1371/journal.pone.0349664
Read the complete primary study ↗ · Creative Commons Attribution licence
From the researchers
Abstract
This study evaluates a dual dietary strategy in African catfish (Clarias gariepinus): optimizing fishmeal replacement and assessing unbalanced, low-cost feeding risks. Five diets were tested over 12 weeks: four isonitrogenous diets (T1–T4, 35% crude protein) with graded fishmeal replacement using poultry by-product meal (PBM) and brewer’s yeast (Saccharomyces cerevisiae), and one unbalanced diet (T5, 100% PBM without carbohydrates, lipids, or micronutrients). A total of 125 fish (initial weight 47.49 ± 0.18 g) were distributed across five 1 m³ tanks (25 fish/tank; n = 1 tank/diet) and fed twice daily at 3% body weight. Growth, hepatic enzymes [alanine/aspartate aminotransferase (ALT/AST)], cholesterol, and hematological parameters [hemoglobin (Hb), hematocrit (Hct), lymphocytes] were measured. Fish fed T2 (15% fishmeal, 20% PBM, 5% yeast) showed the highest daily weight gain (4.36 ± 0.02 g/day), best feed conversion ratio (FCR = 1.32), lowest ALT (18.53 ± 0.37 U/L) and AST (22.09 ± 0.45 U/L), reduced cholesterol (135.53 ± 2.37 mg/dL), and highest Hb (10.89 ± 0.37 g/dL) and Hct (28.76 ± 0.91%). Conversely, T5-fed fish exhibited poor growth (1.97 ± 0.03 g/day), elevated hepatic enzymes, increased cholesterol, and hematological signs of impaired erythropoiesis and chronic immune activation. Diets T3 and T4 showed intermediate performance. Strong negative (r = −0.99) and positive (r = +0.98) correlations linked daily weight gain with ALT and Hct, respectively. These findings indicate that protein quality and dietary balance outweigh crude protein content for fish health and performance. Combining moderate fishmeal with PBM and yeast offers a sustainable strategy to reduce fishmeal reliance, whereas the 100% PBM diet highlights risks of unbalanced feeds in resource-limited settings. These results provide preliminary evidence supporting strategic fishmeal replacement, underscoring the need for validation in fully replicated trials.
1. Introduction
Aquaculture now supplies nearly half of the world’s seafood and plays a critical role in global food security, particularly in developing regions [1]. African catfish (Clarias gariepinus) is a key species in freshwater aquaculture due to its rapid growth, environmental tolerance, and high market demand across Africa, Asia, and the Middle East [2]. However, expanding production is constrained by the rising cost and limited availability of fishmeal, the primary protein source in commercial aquafeeds.
Fishmeal offers a balanced amino acid profile and high digestibility (>90%), but its global production has remained stagnant at around 5 million metric tons annually, while aquaculture output grows at over 5% per year [3; 4]. This imbalance makes fishmeal responsible for 50–70% of feed costs in many operations [5] and raises ecological concerns related to overfishing of forage fish stocks [6].
Reading this evidence
Use the full paper to check the study design, participant selection, comparator and outcome definitions before drawing a practical conclusion. An association does not by itself show cause and effect. A reported performance measure needs its denominator and uncertainty. A finding from a particular facility, sample or time period should retain that scope when it is discussed elsewhere.
This briefing makes the source accessible within the wider research & evidence desk. It does not assess an individual patient or certify a product. When considering relevance to another health system, examine the original authors’ account of context and limitations, then seek local implementation evidence. The related reporting below provides other studies to read alongside this one; it is a topic connection, rather than a claim that their results are directly comparable.
© 2026 Nader Iskandar Hamwi, Hamam Adib Altajer. Excerpts reproduced under CC BY. Selection, formatting and contextual notes by Health Signal. The researchers are the authors of the source study, not members of Health Signal’s staff.
