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Comprehensive Assessment of Bacterial Pathogens Affecting Nile Tilapia and Their Control Strategies: Implications for Aquatic and Public Health Cover

Comprehensive Assessment of Bacterial Pathogens Affecting Nile Tilapia and Their Control Strategies: Implications for Aquatic and Public Health

Open Access
|Jan 2026

Figures & Tables

Figure 1.

Dietary supplementation of probiotics live microorganisms used against different bacterial diseases
Dietary supplementation of probiotics live microorganisms used against different bacterial diseases

Figure 2.

Use of Bacillus as a probiotic against pathogenic bacteria in fish
Use of Bacillus as a probiotic against pathogenic bacteria in fish

Major bacterial diseases, vector, influence, treatments of economically important fish Oreochromis niloticus

DiseaseCausative agentsClinical signsStressor contributing to diseasesTreatmentsCountryReferences

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Motile Aeromonas septicaemia (MAS)Aeromonas hydrophila and other related Aeromonas speciesLoss of body balance; lethargic swimming; gasping at the water surface; external hemorrhage; exophthalmia; swollen abdomen; frequent high mortalities, ulcer, congestion hemorrhagic, skin darkness fin rot, stunted growth, exophthalmos, skin ulcersStress caused by high water temperature, water pH changes, low dissolved oxygen, high levels of ammonia and nitrites, high stocking density, parasitic infections, rough handling and transportationDisinfectants (KMnO4 at 4–10 mg/L for 1 h or 2–4 mg/L indefinite immersion), antibiotics (oxytetracycline as feed additive at 50 mg/kg fish/d for 12–14 d, 21 d withdrawal, probiotics (Enterococcus faecium at 8 g/kg feed for 45 d) Saccharomyces cerevisiae at 5 g/kg feed for 12 weeks), and various vaccinesEgypt MalaysiaMonir et al. (2020)
Prabu et al. (2019)
Stratev and Odeyemi (2017)
StreptococcosisStreptococcus spp. including S. agalactiae, S. iniae, S. dysgalactiae and Enterococcus spp.Red discoloration of the skin; lethargic; erratic swimming; exophthalmia with corneal opacity and hemorrhage in eyes; abdominal distension; skin hemorrhaging around the anus, the base of fins and anus, around the mouth, and in operculum; enlarged and nearly black spleen; and high mortalityIntroduction of contaminated water and/or fry, high stocking density, high water temperature, high ammonia, low dissolved oxygen, unsuitable pH, poor husbandry managementAntibiotic in feed: erythromycin at 50 mg/kg fish/d for 12 d; oxytetracycline at 75–100 mg/kg fish/d for 14 days. Various commercial vaccinesColombiaPrabu et al. (2019), Zamri-Saad et al. (2014)
Thailand
Egypt
Malaysia
ColumnarisFlavobacterium columnareFin rot; necrotic lesions on skin and gills; irregular whitish to grey patches on the skin and/or fins; high mortality ratesPoor environmental conditions, high stocking densities, high organic load, and high-water temperatureKMnO4 to the water at 2 mg/L; 20 min bath in CuSO4 at 37 mg/L or depending on alkalinity, indefinite immersion with CuSO4 at 0.5–3 mg/LBrazilDeclercq et al. (2013); Prabu et al. (2019)
VibriosisVibrio spp.Septicemia; lethargy; anorexia; hemorrhages along the external body surface and the base of the fins; and high mortalityCaused by stress, poor water quality, low water temperature, and bad management practicesDietary inclusion of antibioticEgyptPrabu et al. (2019)
EdwardsiellosisEdwardsiella ictaluri, E. tardaAbnormal swimming; hemorrhages at the base of fins, operculum, belly, mouth, and vent; exophthalmia; bloody fluid in body cavity; swollen, dark red spleen; pale, mottled liver; and swollen, soft kidneyImbalanced environmental conditions, such as high temperature, high organic load, and poor water qualityDietary inclusion of antibioticUnited States,El-Yazeed and Ibrahem (2009); Nhinh et al. (2022); Park et al. (2012)
Venezuela,
Taiwan and
Japan,
Norway
YersiniosisY. ruckeriFocal hyperplasia, desquamation in the secondary lamellae and hemorrhages in the gill arch, skin injuries, acute or chronic enterosepticemia and hemorrhagic zonesOvercrowding of fish and water qualityAntimicrobial drugs, pesticides, probiotics phytogenic agents, yeast products, Omega 3-chitosan nanoparticles and antisepticsEgyptKumar et al. (2015); Aly et al. (2012); Rutherfurd-Markwick and Gill (2004); Selim and Reda (2015); Alemayehu et al. (2018); Eissa et al. (2020)
FrancisellosisFrancisella noatunensis and subsp. orientalisSplenomegaly and granulomas, bleeding around the pectoral fins, anorexia, erratic swimming and exophthalmosPoor management of pond and high stocking densitiesAutogenous whole cell-adjuvanted intravenous vaccineUnitedShahin et al. (2019); Pulpipat et al. (2019)
Kingdom and Taiwan
Summer syndromeCitrobacter freundiiHyperplasia, desquamation in the secondary lamellae and hemorrhages in the gill arch, pale liver, distended abdomen, watery kidney, focal hyperplasia, desquamation in the secondary lamellae and hemorrhages in the gill archContaminated water and high stocking densitiesBacteriophage therapyIndia and BrazilEl Asely et al. (2020); Jia et al. (2020)
Pseudomonad septicemiaPseudomonas fluorescens and Pseudomonas aeruginosaExophthalmia, red spot on skinOverpopulation, low temperature and injuriesYucca extract (feed additive)EgyptHal and Manal (2020); Osman et al. (2021); El-Keredy and Naena (2020)
Piscirickettsiosis (salmonid-septicemic disease)Piscirickeittsia salmonisNecropsy, occasional cutaneous hemorrhage, exophthalmia, enlarged spleens with multiple white granulomas, gills epithelial hyperplasia and loss of interlamellar spaces, anorexia, lethargy, respiratory distress, skin darkening and surface swimmingWater temperature fluctuations and strong stormsTetracycline, and clarithromycinTaiwanToranzo et al. (2005); Mauel et al. (2003)
StaphylococcosisStaphylococcus aureusRed spots on the skinWater temperature fluctuations and pH of waterPhytogenic feed additives and Boswellia serrata resin extract (BSRE) supplementationPakistanMontaser et al. (2021); Fatima (2014); Pridgeon and Klesius (2012)
Kenya
FlexibacteriosisFlavobacterium columnareNecrosisOverpopulation, splenomegaly infected fish tissue, skin, gills and finsCentella asiatica aqueous extract and β-glucanEgyptEl-Tawab et al. (2020);Amphan et al. (2019)

Pathogenic bacteria, key characteristics and recent control in Nile tilapia

Pathogenic bacteriaKey characteristicsControlReferences
Aeromonas hydrophilaGram-negative, rod-shaped, motile. Causes ulcers, hemorrhages, and fin rot.Antibiotic treatments, probiotics, immunization.Rivas et al. (2023); Hassanin et al. (2024)
Streptococcus iniaeGram-positive, cocci, causes systemic infections and lesions in muscle.Vaccination, early detection, and hygiene practices.Wang et al. (2021)
Edwardsiella ictaluriGram-negative, facultative anaerobe, causes septicemia.Vaccination, environmental control, antibiotics.Abu-Zahra et al. (2024); Ghani et al. (2024)
Vibrio alginolyticusGram-negative, halophilic, associated with skin lesions and fin rot.Salt baths, antimicrobial treatments, biosecurity.Abotaleb et al. (2024)
Flavobacterium columnareGram-negative, filamentous, causes columnaris disease (skin ulceration).Immunostimulants, bacteriophage therapy, water quality management.Zahran and Risha (2013)
Yersinia ruckeriGram-negative, motile, associated with red mouth disease in fish.Antibiotics, vaccination, good water quality management.Alemayehu et al. (2018)
Pseudomonas fluorescensGram-negative, motile, causes gill disease and systemic infections.Antibiotic treatment, improving water quality, and biosecurity.Moharam et al. (2024)
Vibrio vulnificusGram-negative, halophilic, associated with wound infections.Saltwater baths, antibiotics, and early detection.Cai et al. (2024)
Francisella spp.Gram-negative coccobacillus, causes francisellosisLive-attenuated or DNA vaccinesMeyer et al. (2025)
Staphylococcus aureusGram-positive, causes staphylococcosisBoswellia serrata resin extract (BSRE) supplementationMontaser et al. (2021)
Lactococcus garvieaeGram-positive, causes piscine lactococcosisAdjuvant, inactive whole cell vaccineBwalya et al. (2020)
DOI: https://doi.org/10.2478/aoas-2025-0046 | Journal eISSN: 2300-8733 | Journal ISSN: 1642-3402
Language: English
Page range: 211 - 235
Submitted on: Oct 10, 2024
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Accepted on: Apr 29, 2025
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Published on: Jan 30, 2026
In partnership with: Paradigm Publishing Services
Publication frequency: Volume open

© 2026 Muhammad Luqman Khan, Habib Ul Hassan, Shahnaz Rashid, Sumbul, Ghazi Alatawi, Ghulam Abbas, Muhammad Ahsan Raza, Rizwana Abdul Ghaffar, Roohi Kanwal, Muhammad Kabir, Naseem Rafiq, Mary Mahwish, Yousef Abdal Jalil Fadladdin, published by National Research Institute of Animal Production
This work is licensed under the Creative Commons Attribution 3.0 License.