This study characterises morphologically Trichodina heterodentata Duncan, 1977 from channel catfish, Ictalurus punctatus (Rafinesque, 1818) in the State of Santa Catarina, Brazil. Body and gill smears were air-dried at room temperature, impregnated with silver nitrate and/or stained with Giemsa. Ten characteristics were selected to compare the present material with other morphological characterisations of T. heterodentata. Prevalence rate was 100%, mean intensity 89,333.70 (3,125 to 299,100 parasites per host). Trichodina heterodentata was considered medium-sized trichodinid with mean body diameter 59.4 ± 8.5 µm, denticulate ring 38.5 ± 4.5 µm, adhesive disc 60.2 ± 6.7 µm diameter and 24.4 ± 1.6 denticles. In relation to previous reports of T. heterodentata this material resembles in 90% of the analysed characters. This work confirms the biometrical variation that exists in the different populations of T. heterodentata. A list of hosts and comparative measurements of T. heterodentata are presented and the channel catfish is considered a new host.Keywords: channel catfish, trichodinid, Trichodina heterodentata, morphology. Trichodina heterodentata foi considerado um tricodinídeo de tamanho médio com a média do diâmetro do corpo de 59,4 ± 8.5 µm, anel denticulado 38,5 ± 4,5 µm, disco adesivo 60,2 ± 6,7 µm de diâmetro e 24,4 ± 1,6 dentículos. Em relação a registros prévios de T. heterodentata, 90% das características foram semelhantes. Este trabalho confirma a variação biométrica que existe em diferentes populações de T. heterodentata. Uma lista de hospedeiros e medidas comparativas de T. heterodentata são apresentadas e o bagre-do-canal considerado um novo hospedeiro. Primeiro registro dePalavras-chave: bagre do canal, tricodinídeo, Trichodina heterodentata, morfologia.

This study evaluated the trace elements and parasitological indices in Nile tilapia examined from two different facilities, named as swine-consorted, using pig manure, and monoculture. For trace element analysis, the fish muscle tissue was collected individually in each facility. Each portion was weighed, dried in a stove at 60°C for 48 h and analyzed by Energy Dispersive X-ray Fluorescence Spectrometry (EDXRF). Parasitological analysis followed the routine method for parasites collection, quantification and identification. The predominant element was zinc (Zn) followed by iron (Fe) and arsenic (As) in fish from both facilities. Fish from swine-consorted system had greater values of abundance and mean intensity of trichodinids and fish from monoculture showed higher abundance and mean intensity of monogeneans. Nevertheless, no signs of damage to fish production was observed. The contents of the elements Zn, Fe, As, cooper (Cu) and mercury (Hg) were above of the maximum permitted limits recommended by the Brazilian legislation.