Haematological and histological changes to Oreochromis niloticus juveniles exposed to sub-chronic doses of cypermethrin in a flow-through bioassay

Haematological and histological changes to Oreochromis niloticus juveniles exposed to sub-chronic doses of cypermethrin in a flow-through bioassay | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Article Haematological and histological changes to Oreochromis niloticus juveniles exposed to sub-chronic doses of cypermethrin in a flow-through bioassay A. J. YAJI, E. O. Ogueji, J. J. Ekpenyong, Imtiyaz Qayoom This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-7224837/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract Cypermethrin (CYP), a type II pyrethroid widely used for insect control in agriculture, has contaminated aquatic ecosystems, posing threats to fish health. Researchers evaluated how sub-lethal toxicity influenced white blood cell count (WBCC), red blood cell count (RBCC), haematocrit (PCV %), and haemoglobin (Hb) levels (g/dl). Mean corpuscular haemoglobin (MCH), mean corpuscular haemoglobin concentration (MCHC), and mean corpuscular volume (MCV) served as erythrocyte indicators. Fish were collected from ponds and acclimatized in the laboratory. Haematological samples were collected after intervals of 2, 6, and 8 weeks; gill and liver tissues were examined after 8 weeks from control and CYP-exposed fish at low (0.5 µg L⁻¹) and high (1.8 µg L⁻¹) concentrations. RBCC, Hb, PCV, MCV, and MCH levels significantly declined (P≤0.05) after 2 weeks in treated groups. WBCC significantly increased in a time-and dose-dependent manner. Percentage lymphocytes exhibited a mixed trend, while neutrophils increased at the highest CYP concentration. CYP exposure caused mucus secretion, vacuolation, oedema, hyperplasia, and hypertrophy in gill primary lamellae. Liver tissues showed steatosis, coagulation necrosis, and sinusoidal gaps. These findings indicate that sub-lethal CYP exposure negatively impacts fish health. Health sciences/Diseases Biological sciences/Ecology Earth and environmental sciences/Ecology Earth and environmental sciences/Environmental sciences Biological sciences/Zoology Fish health freshwater fish hematology histopathology pollution Full Text Additional Declarations No competing interests reported. Cite Share Download PDF Status: Posted Version 1 posted You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-7224837","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Article","associatedPublications":[],"authors":[{"id":512396799,"identity":"40f527bc-8426-47db-843e-b308a87d635d","order_by":0,"name":"A. J. 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Researchers evaluated how sub-lethal toxicity influenced white blood cell count (WBCC), red blood cell count (RBCC), haematocrit (PCV %), and haemoglobin (Hb) levels (g/dl). Mean corpuscular haemoglobin (MCH), mean corpuscular haemoglobin concentration (MCHC), and mean corpuscular volume (MCV) served as erythrocyte indicators. Fish were collected from ponds and acclimatized in the laboratory. Haematological samples were collected after intervals of 2, 6, and 8 weeks; gill and liver tissues were examined after 8 weeks from control and CYP-exposed fish at low (0.5 µg L⁻¹) and high (1.8 µg L⁻¹) concentrations. RBCC, Hb, PCV, MCV, and MCH levels significantly declined (P≤0.05) after 2 weeks in treated groups. WBCC significantly increased in a time-and dose-dependent manner. Percentage lymphocytes exhibited a mixed trend, while neutrophils increased at the highest CYP concentration. 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