ABSTRACT Coating medicated fish feed with a polymer minimizes the chances of drug leaching into the water. Tambaqui (Colossoma macropomum) is an economically important Amazonian fish frequently parasitized by the acanthocephalan Neoechinorhynchus buttnerae. In this study, we compared the effect of ethylcellulose (EC 0.75%) coating of feed medicated with the antihelminthic albendazole (ABZ 10 mg kg bw-1) and uncoated feed on treatment efficacy and bioaccumulation of ABZ in naturally parasitized tambaqui during 35 days. Treatment efficacy was 34% and 66% in fish fed uncoated and coated feed, respectively, but did not vary significantly among treatments. Total ABZ residue reached concentrations from 122.0 to 151.7 ng g-1, and did not vary significantly among treatments. The biomagnification factor was low, ranging from 0.0003 to 0.0004. EC coating did not significantly affect the efficacy of ABZ treatment and did not interfere with ABZ bioaccumulation in the edible tissue of tambaqui. water Colossoma macropomum buttnerae study 0.75% 075 0 75 1 bw1 bw bw-1 3 days 34 66 respectively treatments 1220 122 122. 1517 151 7 151. g1, g1 g 1, g-1 low 00003 0003 0.000 00004 0004 0.0004 0.75 07 bw- 6 12 15 g- 0000 000 0.00 0.7 00 0.0 0.

RESUMO Revestir ração medicada para peixes com um polímero minimiza a lixiviação do fármaco na água. Tambaqui (Colossoma macropomum) é um peixe amazônico economicamente importante, frequentemente parasitado pelo acantocéfalo Neoechinorhynchus buttnerae. Neste estudo, comparamos o efeito do revestimento com etilcelulose (EC 0,75%) de ração medicada com o anti-helmíntico albendazol (ABZ, 10 mg kg-1 pc) e ração não revestida sobre a eficácia do tratamento e bioacumulação de ABZ em tambaquis naturalmente parasitados. A eficácia foi de 34% e 66%, em peixes alimentados com ração não revestida e revestida, respectivamente, mas não variou significativamente entre tratamentos. O resíduo total de ABZ atingiu concentrações de 122,0 a 151,7 ng g-1, mas não variou significativamente entre os tratamentos. O fator de biomagnificação foi baixo, variando entre 0,0003 e 0,0004. O revestimento com EC não afetou significativamente o tratamento com ABZ e não interferiu na bioacumulação de ABZ no tecido comestível do tambaqui. água Colossoma macropomum importante buttnerae estudo 0,75% 075 0 75 antihelmíntico anti helmíntico ABZ, (ABZ 1 kg1 kg kg- pc parasitados 34 66 66% respectivamente tratamentos 1220 122 122, 1517 151 7 151, g1, g1 g 1, g-1 baixo 00003 0003 0,000 00004 0004 0,0004 tambaqui 0,75 07 3 6 12 15 g- 0000 000 0,00 0,7 00 0,0 0,

Abstract Tambaqui is the second native fish most produced species in Brazil. Currently, tambaqui fish farms deals with serious sanitary problems due to the prevalence of the parasite Neoechinorhynchus buttnerae. However, the prevalence of the acanthocephalan parasite infections depends on the resistance and tolerance interactions between the host organisms and parasites. The immune response against parasites is divided between innate and acquired immunity. The innate defense is a result of physical barriers, cellular and humoral compounds. Acquired defense occurs through the production of antibodies (humoral) and is mediated by cells, mainly by type 2 T helper lymphocytes. Most parasites secrete a variety of immunomodulatory compounds that allow coexistence with the host and chronicity of the parasite. The host-parasite relationship is complex and makes prevention and treatment difficult. However, some studies show that the use of immunostimulants may have “systemic” effects. These include improvement of the intestinal mucosa health and also in the production of cellular and humoral compounds in the whole body, thus assisting treatment and control. As such, it is important to understand the mechanisms of resistance and tolerance in the host organisms so that prevention and treatment measures can be effective.