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.

Embryonic and early larval development of two marine angelfish, Centropyge bicolor and Centropyge bispinosa.

Marine angelfish (family: Pomacanthidae) are among the most sought-after fish species in the saltwater aquarium trade. However, there is a lack of information in the literature on their early ontogeny. The objective of this study was to describe the embryonic and early larval development of two dwarf angelfish, the bicolour angelfish, Centropyge bicolor and the coral beauty angelfish, Centropyge bispinosa. The eggs of these two species were obtained from spontaneous spawning of the broodstock fish in captivity and incubated at 26.0 ± 0.2°C throughout the study. Fertilized eggs (n = 15) of both species are transparent, pelagic and spherical; the mean diameters of the eggs were measured at 703.6 ± 7.8 µm for C. bicolor and 627.6 ± 7.8 µm for C. bispinosa. The eggs of both species possessed a narrow perivitelline space, smooth and thin chorion, a homogenous and non-segmented yolk as well as a single oil globule. Overall, the observed embryonic development pattern of C. bicolor and C. bispinosa was very similar, and the main difference was the embryonic pigmentation pattern, which only became evident close to hatching. Larvae of both species started hatching at 13 h 30 min after fertilization, and the larval characteristics of both species also showed high levels of similarities. However, the mouth opening time for C. bicolor was 72 h after hatching (AH) and 96 AH for C. bispinosa. In general, the observed early ontogeny of C. bicolor and C. bispinosa also resembled that of other Centropyge species documented in the literature.

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.

Two Perkinsus spp. infect Crassostrea gasar oysters from cultured and wild populations of the Rio São Francisco estuary, Sergipe, northeastern Brazil.

Brazilian production of bivalve molluscs is small but expanding, especially in the northeastern region where the native oysters Crassostrea rhizophorae and C. gasar are abundant, and tropical weather promotes their rapid growth. Studies on bivalve pathology are scarce in Brazil, with only a few employing techniques for detecting protozoan pathogens listed by the World Organisation for Animal Health (OIE). In 2008, a Perkinsus sp. was reported for the first time in Brazil, infecting C. rhizophorae oysters from a wild population in Ceará state, NE Brazil. Recently P. marinus was detected in the same oyster species in nearby Paraíba state. These findings highlighted the need to expand knowledge on the presence and impacts of Perkinsus spp. on Brazilian oyster populations. The current investigation evaluated Perkinsus sp. infections among wild and cultured C. gasar mangrove oysters from the estuary of the Rio São Francisco, Sergipe state, NE Brazil. Our results show that Perkinsus sp. infections occurred commonly in oysters of both groups, at prevalences that were frequently higher among cultured oysters. Prevalences varied seasonally, with maximum values during summer (January) of 57% and 80% for wild and cultured oysters respectively, and minimum values during winter (July). Results of DNA sequencing, in situ hybridization assays, and phylogenetic analyses showed dual- and single-pathogen infections by P. marinus and/or P. olseni in the tested oysters.