First report of thyroid goiter in the marine ornamental fish Gramma brasiliensis.

Enlargement of the thyroid gland is referred to as goiter. In captive fish, goiter may be associated with iodine deficiency in water or diet, exposure to goitrogenic factors such as a high environmental nitrate concentration or water treatment with ozone. This report describes the occurrence of goiter in a marine ornamental fish raised in a research laboratory, the Brazilian basslet Gramma brasiliensis. From 2016 to 2023, we observed progressively growing tumour-like masses in the pharyngeal cavity and along the gill arches of approximately 20 adult individuals. This abnormal growth impaired the ingestion of food and caused dyspnoea, leading the animals to death within a few months after the first appearance of the mass. The samples were submitted to histological analyses, which revealed moderate to severe, diffuse, hypertrophy and hyperplasia of thyroid follicular cells with most lacking colloids. This is the first report of goiter in the Brazilian basslet. Although it is not clear why this condition develops in this species, we recommend keeping nitrate levels to a minimum and monitoring water iodine concentrations regularly until future studies investigate the possible causes and adequate treatment for this species.

O aumento da glândula tireóide é conhecido como bócio. Em peixes em cativeiro, o bócio pode estar associado à deficiência de iodo na água ou na dieta, à exposição a fatores goitrogênicos, como alta concentração de nitrato ou ao tratamento da água com ozônio. O presente relato descreve a ocorrência de bócio em um peixe ornamental marinho criado em laboratório de pesquisa, o Gramma brasiliensis. De 2016 a 2023, observamos crescimento progressivo de massas semelhantes a tumores na cavidade faríngea e ao longo dos arcos branquiais de aproximadamente 20 indivíduos adultos. Esse crescimento anormal prejudicou a ingestão de alimentos e causou dispneia, levando os animais à morte em poucos meses, desde o início do aparecimento das massas. As amostras foram submetidas à análise histológica, evidenciando hipertrofia e hiperplasia moderada a grave, difusa, de células foliculares tireoidianas, sendo a maioria delas desprovida de colóide. Este é o primeiro relato de bócio em grama brasileiro. Apesar da razão pouco clara para o desenvolvimento desta condição nesta espécie, recomendamos manter os níveis de nitrato ao mínimo e monitorar regularmente as concentrações de iodo na água até que próximos estudos investiguem as possíveis causas e o tratamento adequado para esta espécie.

Spawning, egg and larval description of the brazilian basslet Gramma brasiliensis Sazima, Gasparini & Moura, 1998 in captivity.

Brazilian basslet Gramma brasiliensis is a fish highly appreciated by the marine ornamental industry. There is an increasing interest in the development of a breeding protocol for this species. However, descriptions of the reproductive biology, eggs and larval development are scarce. This study was the first to describe the spawning, eggs and larvae of G. brasiliensis in captivity, including mouth size information. Six spawning events produced egg masses with 27, 127, 600, 750, 850, and 950 eggs. Larger egg masses showed embryos with at least two different developmental stages. Eggs are spherical (∼1.0 mm diameter), held together by filaments entangling chorionic projections. Larvae with fewer than 12 hph (hours post-hatch) presented 3.55 mm standard-length, well developed eyes, fully absorbed yolk sac, an inflated swim bladder and mouth opened. Exogenous feeding on rotifers began within 12 hph. The average mouth width at first feeding was 0.38 mm. The first settled larva was noted by day 21. This information should help to determine appropriate diets and prey-shift time during the larviculture of the species.

Thermal influence on the embryonic development and hatching rate of the flameback pygmy angelfish Centropyge aurantonotus eggs.

The flameback pygmy angelfish Centropyge aurantonotus, highly appreciated and valued by the aquarium market, is heavily harvested and traded. Temperature is one of the abiotic factors that has the most influence on fish development, especially in the early stages of life. For captive production, it is essential to know the appropriate environmental parameters for each species. In this sense, this study aimed to evaluate the influence of temperature on the embryonic development and hatching rates of C. aurantonotus incubated at six different temperatures (20, 22, 24, 26, 28, 30°C). Embryonic development events were very similar in terms of morphological and chronological characteristics compared with other species of the genus Centropyge. Incubation time was inversely proportional to temperature. The treatment at 22°C required twice the time of that required by 30°C treatment for hatching to occur. The best incubation temperature range was 24-28°C. Values below 22°C and at 30°C showed lower hatching rates compared with other treatments. Based on these results, the recommended temperature at which to incubate C. aurantonotus eggs is between 24-28°C.