Post-embryonic development of water- and airbreathing organs of Anabas testudineus (Bloch)

The development of respiratory surfaces in post-embryonic stages of Anabas testudineus was studied using morphometric methods on serial sections through the pharyngeal region of specimens obtained by induced breeding of known parentage. The larvae and fry were fixed in glutaraldehyde and osmium tetroxide. In the young stages aquatic respiration was found to be obligatory. The hatchlings come out of the egg membranes about 10 h after fertilization. During the yolk-sac stages gaseous exchange takes place through the well vascularized skin. The gills start differentiating at about 24 h and become functional at about 39 h. The labyrinthine organs begin to develop after 51 h but the hatchlings do not take an air breath until they reach 13–14 days. The appearance of scales at 11–14 days probably hinders cutaneous respiration and is correlated with the onset of aerial respiration.
Morphometric analysis using stereological methods shows high surface: volume ratios for the gills and labyrinthine organs as adaptations to gas exchange function. A marked decrease in surface: volume ratio for the suprabranchial cavities between 7 and 11 days indicates an increase in volume to accommodate the expanding labyrinthine plates which retain a fairly constant surface: volume ratio.     

Surface area of the respiratory organs of the Climbing perch, Anabas testudineus (Pisces: Anabantidae)

Measurements have been made of the surface area of the gills and accessory respiratory organs of Anabas in the weight range 1–120 g, and the data analysed with respect to body weight using logarithmic transformations. The slope of the regression line for total gill area (0–615) is less than that found in most fish, the number of secondary lamellae/mm decreased more rapidly with body weight than for most water-breathing species (h = -0.152). The gill area of Anabas is relatively small but when the area of the accessory organs is added, the total respiratory area is of the same order as inactive water-breathing fish. The regression coefficient for combined areas of labyrinthine organs and lining of the suprabranchial chambers (0.713) exceeds that for the gills and together with other evidence (including estimates of diffusing capacity from morphological measurements), indicates an increasing importance of air-breathing of larger specimens. The average surface area of the accessory organs available for 1 ml of air within the suprabranchial chambers was found to be 2226 mm².     

Aluminium accumulation and distribution in the freshwater clams (unionidae)

1. Freshwater unionids (Anodonta anatina L. and Unio pictorum L.) were exposed to aluminium (300 and 900 μg/l, nominal) in continuous (3 weeks) and fluctuating (24 days) acid exposures.2. In addition, accumulation was monitored for 2 weeks under semi-static acid (pH4-5) and circumneutral (pH 6.6-8.3) conditions in hard (35 mg Ca/l) and soft water (3.5 mg Ca/l).3. In addition, a fluctuating exposure of 24 days, consisting of three intermittent pulses which combined low pH (4–5) and high Al (900 μg/l) concentration, was performed.4. The various organs of A. cygnea, collected from a watershed with relatively high heavy metal concentrations, were analyzed for their Al and Cd concentrations.5. The ultimate order of the Al and Cd concentration in these clams was identical: kidney ≥ midgut gland ≥ rest ≥ gill ≥ mantle.6. During the 3 weeks of exposure, the Al concentration in the gills and kidney increased linearly, and saturation level was not reached.7. The Al concentration in the calcium concretion material isolated from the gills was lower than that of the whole organ.8. An elimination period of 12 weeks was needed to reach the background level of Al in the gills, whereas in the kidney the initial Al concentration was reached after 4 weeks of elimination.9. In both species, the ambient pH had a significant effect on the Al accumulation in the gills, whereas the effect of the water hardness was only of minor importance.10. Rapid elimination of the Al accumulated in the gills of U. pictorum during the episodic 3-day exposure was recorded.     

Exploration of polyacrylamide microplastics and evaluation of their toxicity on multiple parameters of Oreochromis niloticus

Due to the increased production of polyacrylamide microplastics in the environment impacting the adverse effects on aquatic organisms have become a global concern. The present study aimed to evaluate the toxicity of different concentrations (0.018, 0.03 0.09 g/1) of polyacrylamide microplastics on Oreochromis niloticus. Polyacrylamide microplastics were characterized by Fourier transform infrared and Raman spectroscopy. The FTIR technique revealed the spherical morphology and size range of polyacrylamide (0.1–0.4 mm) with 99 % purity. Raman Spectroscopy results showed peaks around (1100 cm^?1 and 1650 cm^?1) in gills, these peaks confirmed the presence of polyacrylamide microplastics in the gills of Oreochromis niloticus. Polyacrylamide microplastics significantly shortened the antioxidant enzymes (Catalase and Reduced glutathione) proceedings and the increase was observed in Malondialdehyde and Lipid peroxide levels in high-dose treated groups. Moreover, total protein contents were expressively increased, while other blood parameters (AST, ALP, ALT) were significantly decreased. Hemoglobin (g/dl), Erythrocyte (106/µl) and TLC (1x10⁹/l) levels were reduced significantly (p < 0.05) in high concentrations. The administration of polyacrylamide microplastics induced different histological changes in the gills, liver and intestine of O. niloticus. It was concluded that polyacrylamide microplastics are toxic agents having harmful effects on fish health.     

Fine structure of the respiratory organs of the Climbing perch, Anabas testudineus (Pisces: Anabantidae)

An electron microscopic study has been made of the three respiratory organs of climbing perch. The gill structure is similar to that of the other telcosts but the thickness of the water/blood barrier is much greater, being as great as 20 μm in some specimens. The increased thickness is due to a multilayered epithelium which is thinner (3.5–7 μm) over the marginal channel of the secondary lamellae. The other two main layers, basement membrane and pillar cell flange, are relatively thin (about 1 μm).
The pillar cells have a typical structure, but in certain regions they are contiguous with one another and line well-defined blood channels. Some of the columns of basement membrane material in such regions may be common to adjacent pillar cells.
The air-breathing organs are (a) the lining of the suprabranchial chambers , and (b) the labyrinthine plates attached to the dorsal region of branchial arches. Electron microscopy showed that their structure is well adapted for gas exchange, the air/blood barriers being only 0.12–0.3 μm, comprising an epithelial layer, basement membrane, and thin capillary endothelium. The many parallel blood channels of the respiratory islets of both organs are separated by pillar-like structures which differ from the pillar cells of the secondary lamellae. Thus the hypothesis that the air-breathing organs represent modified gills is not supported by this study.
The fine structure of the non-respiratory region of the air-breathing organs is similar to that of the skin, and includes chemoreceptor-like cells. Evidence concerning the possible homology of pillar cells with plain muscle cells is discussed.     

In vivo and in vitro effects of cadmium on selected enzymes in different organs of the fish Barbus conchonius ham. (Rosy Barb)

1. Enzyme modulation by cadmium in selected organs of the fish, Barbus conchonius (rosy barb), was investigated in vivo (48 hr exposure to 12.6 mg/1 cadmium chloride) and in vitro (10⁻⁶M cadmium chloride).2. The acetylcholinesterase (AchE) activity was depressed in the gills but stimulated in the skeletal muscles and brain in vivo. The hepatic, branchial, and renal acid phosphatase (AcP) activity decreased marginally in vivo but it was significantly increased in the gut and ovary. In vitro, except for the liver, the AcP activity was depressed in the selected organs. Collaterally, gut alkaline phosphatase (A1P) was significantly inhibited but a pronounced stimulation was noted in the kidneys and ovary in vivo. In vitro, the AIP activity was conspicuously elevated in the kidneys and gut, and moderately in the gills.3. Cadmium inhibited the glutamate-oxaloacetate and glutamate-pyruvate transaminases (GOT and OPT) in the liver, gills and kidneys in vivo. In vitro, the GOT and GPT activities were decreased in the liver, gills and kidneys. The lactic dehydrogenase (LDH) was significantly stimulated by Cd in the heart in vivo but in vitro the metal inhibited the enzyme in the gills.4. Enzymes in the liver, followed by those in the kidneys and gills seem to be most seriously affected by Cd poisoning in this fish.     

Early life history timings in marbled rockcod (Notothenia rossii) fingerlings from the South Shetland Islands as revealed by otolith microincrement

Although it has been reported that Notothenia rossii elsewhere hatches in spring, our daily increment back-counting from the capture date in otoliths of fingerlings caught in Potter Cove, South Shetland Islands, in the 2000s, showed two main periods of larval hatching, one in summer (February–March) and another in winter (July). In concordance, the simultaneous presence of two cohorts born the same year was identified in the age/length frequency distribution of fish sampled in spring 2010, which belonged to biological ages 0+ and 1+ and hatched, respectively, in summer and winter–spring. Maximum and minimum ages of pelagic blue-phase and demersal brown-phase fingerlings were, respectively, 227 and 240 days, indicating a demersal settlement after about 8 months from hatching. The estimated growth rate was 0.23–0.33 mm/day, equivalent to that of South Georgia fingerlings and higher than those of other nototheniids of similar size range. Based on early life events associated with the hatching periods, two types of life cycles are hypothesised for South Shetland fingerlings. The pelagic blue-phase fingerlings (6.5–7.6 cm TL, age group 0+) hatched in July (winter cohort), entering in Potter Cove in February–March. The brown-phase fingerlings (6.3–10.6 cm, mostly of age group 0+) hatched in February–March (summer cohort) and were collected in the cove in spring (the smaller specimens) or in summer (the larger ones). Finally, early juveniles (10.7–15.5 cm, age group 1+) hatched in winter, mainly in July (winter cohort), entering in the cove the following year to spend the second winter inshore.     

Effect of heavy metals (Cu,Cd and Pb) on aspartate and alanine aminotransferase in Ruditapes philippinarum (Mollusca: Bivalvia)

The accumulation of cadmium, copper and lead and their effects on aspartate and alanine aminotransferases in digestive gland, gills, foot and soft body in the clam Ruditapes philippinarum were examined. The animals were exposed to different concentrations: Cd (200–600 μg·l⁻¹), Pb (350–700 μg·l⁻¹) and Cu (10–20 μg·l⁻¹) for 7 days. The highest concentrations were found in digestive gland for cadmium and copper, and in gills for lead, and the lowest values were observed in the foot. Aspartate aminotransferase activity (AST), in general, was not inhibited by cadmium, lead or copper during the exposure. Only in clams exposed to cadmium (600 μg·l⁻¹, 7 days) and copper (20 μg·l⁻¹, 5 days) were observed significant differences (P<0.05) in foot and gills, respectively, with respect to control. In the case of alanine aminotransferase activity (ALT), significant differences were observed for cadmium and lead in treated animals with respect to control. With regard to copper, a decrease in ALT was observed in gills and foot exposed to 20 μg·l⁻¹. A significant correlation (P<0.05) was observed between ALT and metal accumulation for cadmium, copper and lead in gills. In the case of soft body, only cadmium and lead showed a significant correlation. In summary, R. philippinarum can be considered a bioindicator species for cadmium and lead accumulation and ALT could be useful as biomarker of sublethal stress for these metals in soft tissues and gills. Only gills can be considered an adequate target tissue for copper.     

Fish Cholinesterases as Biomarkers of Sublethal Effects of Organophosphorus and Carbamates in Tissues of Labeo Rohita

Organophosphates and carbamates are major agrochemicals that strongly affect different neuroenzymes and the growth of various fish species. Here, we study the effect of sublethal concentrations of profenofos and carbofuran on the activity of acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE) and the associated health risk in fish. Labeo rohita fingerlings were exposed to three sublethal concentrations of profenofos and carbofuran. The minimum cholinesterase activities in the brain, gills, muscle, kidney, liver, and blood were after exposure to profenofos (0.06 mg/L). The minimum AChE and BuChE activities in the brain, gills, muscle, kidney, liver, and blood were after exposure to carbofuran (0.28 and 0.198 mg/L). Exposure to both types of pesticides affected the functions of these organs, including metabolism and neurotransmission, to various extents at different exposure concentrations. These findings suggest that they are required to be properly monitored in the environment, to reduce their toxic effects on nontarget organisms     

Cd, Cu, Zn, Se, and Metallothioneins in Two Amphibians, Necturus maculosus (Amphibia, Caudata) and Bufo bufo (Amphibia, Anura)

The accumulation of cadmium, its affinity for metallothioneins (MTs), and its relation to copper, zinc, and selenium were investigated in the experimental mudpuppy Necturus maculosus and the common toad Bufo bufo captured in nature. Specimens of N. maculosus were exposed to waterborne Cd (85???g/L) for up to 40?days. Exposure resulted in tissue-dependent accumulation of Cd in the order kidney, gills > intestine, liver, brain > pancreas, skin, spleen, and gonads. During the 40-day exposure, concentrations increased close to 1???g/g in kidneys and gills (0.64?C0.95 and 0.52?C0.76; n?=?4), whereas the levels stayed below 0.5 in liver (0.14?C0.29; n?=?4) and other organs. Cd exposure was accompanied by an increase of Zn and Cu in kidneys and Zn in skin, while a decrease of Cu was observed in muscles and skin. Cytosol metallothioneins (MTs) were detected as Cu,Zn?Cthioneins in liver and Zn,Cu?Cthioneins in gills and kidney, with the presence of Se in all cases. After exposure, Cd binding to MTs was clearly observed in cytosol of gills as Zn,Cu,Cd?Cthionein and in pellet extract of kidneys as Zn,Cu,Cd?Cthioneins. The results indicate low Cd storage in liver with almost undetectable Cd in liver MT fractions. In field trapped Bufo bufo (spring and autumn animals), Cd levels were followed in four organs and found to be in the order kidney > liver (0.56?C5.0???g/g >0.03?C0.72???g/g; n?=?11, spring and autumn animals), with no detectable Cd in muscle and skin. At the tissue level, high positive correlations between Cd, Cu, and Se were found in liver (all r?>?0.80; ???=?0.05, n?=?5), and between Cd and Se in kidney (r?=?0.76; n?=?5) of autumn animals, possibly connected with the storage of excess elements in biologically inert forms. In the liver of spring animals, having higher tissue level of Cd than autumn ones, part of the Cd was identified as Cu,Zn,Cd?Cthioneins with traces of Se. As both species are special in having liver Cu levels higher than Zn, the observed highly preferential Cd load in kidney seems reasonable. The relatively low Cd found in liver can be attributed to its excretion through bile and its inability to displace Cu from MTs. The associations of selenium observed with Cd and/or Cu (on the tissue and cell level) point to selenium involvement in the detoxification of excessive cadmium and copper through immobilization.     

Expression Profiles of Branchial FXYD Proteins in the Brackish Medaka Oryzias dancena: A Potential Saltwater Fish Model for Studies of Osmoregulation

FXYD proteins are novel regulators of Na⁺-K⁺-ATPase (NKA). In fish subjected to salinity challenges, NKA activity in osmoregulatory organs (e.g., gills) is a primary driving force for the many ion transport systems that act in concert to maintain a stable internal environment. Although teleostean FXYD proteins have been identified and investigated, previous studies focused on only a limited group of species. The purposes of the present study were to establish the brackish medaka (Oryzias dancena) as a potential saltwater fish model for osmoregulatory studies and to investigate the diversity of teleostean FXYD expression profiles by comparing two closely related euryhaline model teleosts, brackish medaka and Japanese medaka (O. latipes), upon exposure to salinity changes. Seven members of the FXYD protein family were identified in each medaka species, and the expression of most branchial fxyd genes was salinity-dependent. Among the cloned genes, fxyd11 was expressed specifically in the gills and at a significantly higher level than the other fxyd genes. In the brackish medaka, branchial fxyd11 expression was localized to the NKA-immunoreactive cells in gill epithelia. Furthermore, the FXYD11 protein interacted with the NKA α-subunit and was expressed at a higher level in freshwater-acclimated individuals relative to fish in other salinity groups. The protein sequences and tissue distributions of the FXYD proteins were very similar between the two medaka species, but different expression profiles were observed upon salinity challenge for most branchial fxyd genes. Salinity changes produced different effects on the FXYD11 and NKA α-subunit expression patterns in the gills of the brackish medaka. To our knowledge, this report is the first to focus on FXYD expression in the gills of closely related euryhaline teleosts. Given the advantages conferred by the well-developed Japanese medaka system, we propose the brackish medaka as a saltwater fish model for osmoregulatory studies.     

Alteration of environmental salinity modulates atrial natriuretic peptide concentrations in the gills of the oyster,Crassostrea virginica

Because gills are frequently important in ion transport and osmoregulation, the present investigation was designed to determine if atrial natriuretic peptides (putative osmoregulatory peptides) are present within the gills of a representative euryhaline osmoconforming invertebrate. Utilizing three radioimmunoassays devised to amino acids 1–30, 31–67, and 99–126 of the 126 amino acid prohormone, the gills of 72 eastern oysters, Crassostrea virginica were examined and each found to contain atrial natriuretic peptides, whose content was approximately one-seventh of that within the heart of the oyster. In high salinity (32 parts per thousand, ppt) the content of atrial natriuretic peptides recognized by each of the three radioimmunoassays was lower at 3 days (P < 0.005) and then became higher (P < 0.001) compared with their content in medium salinity (21 and/or 27 ppt). The content of atrial natriuretic peptides within gills in a low salinity environment (8 ppt) was significantly lower (P < 0.05) at 3, 7, and 14 days compared with their content in either medium or high salinity environments. We conclude that atrial natriuretic peptides are present within the gill tissues of Crassostrea virginica and that their content changes with alterations in environmental salinity. Their lower content at 3 days in high salinity implies a release of stored natriuretic-like peptides that are re-synthesized by 1 week. The decreased content of atrial natriuretic peptides at 3 days, 1 and 2 weeks in low salinity versus medium or high salinity environments suggests that their synthesis is decreased when exposed to a lower salinity in the environment.     

Bioaccumulation and distribution of mercury in the hard clam,Meretrix lusoria (Bivalvia:Veneidae)

1. Total mercury concentration in whole soft parts of the hard clam, Meretrix lusoria, increased significantly with increasing exposure concentrations. It reached 4.247–7.084 and 9.956–13.643 μg T-Hg/g dry weight in 5 and 50 μg/l Hg mercury solution, respectively, against a background level of 1.824–0.577μg T-Hg/g dry weight.2. Bioconcentration factor was 4–6 times higher in 5 μg/l Hg than that of 50 μg/l Hg. An estimated biological half-life of 20.2 and 18.4 days in 5 and 50 μg/l Hg, respectively, were also obtained after 14 days uptake.3. Accumulation of mercury in tissues of the clams was greater in the gills and viscera than in the mantle, adductor, foot, or hemolymph.4. The amount of mercury present in the gills is related to be a linear relationship with the mercury content of viscera.     

Evaluation of copper, lead and arsenic level in tilapia fish in Cempaka Lake (Bangi, Malaysia) and human daily/weekly intake

In recent years, many studies have stated the nutritional benefits of fish consumption: vitamins, proteins and omega-3 fatty acids, which may protect humans from adverse health effects, including heart disease and stroke. This study aimed to evaluate the concentration of Cu, Pb and As in the liver, gills and muscles of tilapia fish (Oreochromis niloticus) and to calculate the weekly intake from eating tilapia collected from Cempaka Lake, Selangor — Peninsular Malaysia during the period between April 2009 to February 2010. The elemental concentrations were determined using inductively — coupled plasma mass spectrometry (ICP-MS). The results showed that all heavy metal concentrations were significantly different among fish organs, and between calendar months. The data showed that Cu levels in liver, gills and muscles were 491.30, 3.70 and 1.82 μg/g dry weight (dw), respectively. Meanwhile Pb levels were 2.71, 1.04 and 0.48 μg/g dw, respectively and As levels were 6.26, 4.18 and 1.79 μg/g dw, respectively. Significant changes occurred in Cu, Pb and As levels in tilapia fish organs in Cempaka Lake over the period of 11 months. Tilapia weekly intake was calculated based on mean Cu, Pb and As concentrations in the muscle of tilapia fish and adult consumption of tilapia in Malaysia which averages at 160 grams per day. Furthermore, tilapia weekly and daily human intakes for Cu, Pb and As were compared with the Provisional Tolerable Weekly Intake (PTWI) established by the JECFA (WHO/FAO) presenting values below the PTWI. Metal levels in fish muscle were found to be lower than the maximum permitted concentrations recommended by various authorities; hence, consumption of tilapia fish from Cempaka Lake is currently safe for humans.     

Cadmium-induced changes in macromolecular synthesis at transcriptional and translational level in gill tissue of sea mussels,Mytilus edulis L.

1. Sea mussels, Mytilus edulis, were exposed to cadmium chloride at 0–500 μg Cd/l for 48 hr. The gills were excised and incubated with protein and RNA precursors. The exposure resulted in a concentration-dependent inhibition of the synthesis of proteins and of RNA. The inhibitory effect was most pronounced in RNA synthesis.2. RNA was extracted from the gills as total RNA or as polyadenylated RNA. The translational activity of RNAs and the induction of mRNA for metallothionein-like proteins were studied by translation in a cell-free system.3. Exposure of the animals to cadmium at 500 μg/l caused a 5-fold increase in proto-oncogene c-fos mRNA.     

Changes of Blue Mussels Mytilus edulis L. Lipid Composition Under Cadmium and Copper Toxic Effect

The lipid and fatty acid composition of the blue mussels Mytilus edulis L. gills and digestive glands was evaluated after 24 and 72 h of cadmium (Cd) and copper (Cu) exposure. Mussels were exposed to different cadmium (10, 100, and 500 μg/L) and copper (5, 50, and 250 μg/L) concentrations. Similar stress response of predominant membrane phospholipids level as well as polyenoic and non-methylene interrupted (NMI) fatty acids content was observed in mussel gills under both cadmium and copper effects. Increased NMI fatty acids level after 24 h, the metal ions treatment suggests that these acids contribute to the protective response to the membrane oxidative stress caused by accumulation of the metals. The content of cholesterol, some minor membrane phospholipids, and storage lipids (triacylglycerols, TAG) in the mussels’ organs alter significantly under the cadmium and copper effect. A two-step response at the digestive glands TAG level depends on the duration of the cadmium and copper treatments (24 and 72 h) on the mussels. The results demonstrate that Cd and Cu impact has adverse effects on gills and digestive glands lipid and fatty acids composition. The type of observed effects varies with the nature and concentration of the metal ions and depends on the role of the metals in the mussels’ life activity.     

Impacts of nanoparticles and phosphonates in the behavior and oxidative status of the mediterranean mussels (Mytilus galloprovincialis)

The current study investigated the exposure of the Mediterranean mussel (Mytilus galloprovincialis) to gold nanoparticles decorated zinc oxide (Au-ZnO NPs) and phosphonate [Diethyl (3-cyano-1-hydroxy-1-phenyl-2-methylpropyl)] phosphate (PC). The mussels were exposed to concentrations of 50 and 100 µg L^-1 of both compounds alone, as well as to a mixture of both pollutants (i.e. Mix). The singular and the combined effect of each pollutant was investigated by measuring the concentration of various metals (i.e., Cu, Fe, Mn, Zn and Au) in the the digestive glands and gills of mussels, their filtration capacity (FC), respiration rate (RR) and the response of oxidative biomarkers, respectively, following 14 days of exposure. The concentrations of Cu, Fe, Mn, Zn and Au increased directly with Au-ZnO NPs in mussel tissues, but significantly only for Zn. In contrast, the mixture of Au-ZnO100 NPs and PC100 did not induce any significant increase in the content of metals in digetsve glands and gills, suggesting antagonistic interactions between contaminants. In addition, FC and RR levels decreased following exposure to Au-ZnO100 NPs and PC100 treatments and no significant alterations were observed after the exposure to 50 µg.L^-1 of both contaminants and Mix. Hydrogen peroxide (H₂O₂) level, GSH/GSSG ratio, superoxide dismutase (SOD), catalase (CAT) and acetylcholinesterase (AChE) activities showed significant changes following the exposure to both Au-ZnO NPs and PC, in the gills and the digestive glands of the mussel. However, no significant modifications were observed in both organs following the exposure to Mix. The current study advances the understanding of the toxicity of NPs and phosphonates on M. galloprovincialis and sets the path for future ecotoxicological studies regarding the synergic effects of these substances on marine species. Moreover, the current experiment suggests that the oxidative stress and the neurotoxic pathways are responsive following the exposure of marine invertebrates to both nanoparticles and phosphonates, with potential antagonist interactions of these substances on the physiology of targeted species.     

Growth performance, haematology and serum biochemistry of African catfish (Clarias gariepinus) fingerlings fed graded levels of dietary fumonisin B1

Fingerlings of Clarias gariepinus were used to evaluate the effect of dietary fumonisin B₁ (FB₁), a mycotoxin produced by Fusarium verticillioides, on growth, haematological and serum biochemical parameters. The fingerlings were sorted, weighed and randomly stocked in 16 plastic tanks at the rate of 20 fingerlings per tank. Fusarium-cultured maize grains containing FB₁ were used to formulate three diets containing approximately 5.0, 10.0 and 15.0 mg FB₁/kg, constituting diets 2, 3, and 4 respectively. These three diets, plus diet 1, which contained non-Fusarium cultured maize grains that served as the control, were used in a 6-week feeding trial. The final weight gains by the fingerlings were significantly (P?<?0.05) influenced by FB₁. The final weights of the fingerlings fed diets 2, 3 and 4 ranged from 70.07 to 87.10% of the controls. The haematocrit, erythrocytes, haemoglobin, mean corpuscular volume (MCV), mean corpuscular haemoglobin (MCH) and the serum protein constituents (total protein, albumin and globulin) values significantly (P?<?0.05) decreased, while the leucocytes, MCV and MCH increased significantly (P?<?0.05) with increase in the dietary FB₁. The total serum protein values of the fingerlings fed diets 2, 3 and 4 were 34.53, 39.42 and 50.17% lower than the total serum protein values of those fed the control diet. These results indicate that Fusarium-contaminated diets containing about 5.0 mg or more FB₁/kg reduced weight gain and significantly altered haematological parameters and serum protein constituents in the fingerlings. These may have a significant impact on physiological activities and may be vital in immunosuppression in the fingerlings with a strong negative impact on subsequent performance of the fish.