Development and sex affect respiratory responses to temperature and dissolved oxygen in the air-breathing fishes Betta splendens and Trichopodus trichopterus.

Ventilation frequencies of the gills (f) and the air-breathing organ (f) were measured in juveniles and adults of the air-breathing betta (Betta splendens) and the blue gourami (Trichopodus trichopterus) in response to temperature and hypoxia. Ventilatory rates were evaluated after 1 h of exposure to 27 °C (control), 23 and 31 °C (PO = 21.0 kPa), after acute temperature changes (ATC) from 23 to 27, and 27 to 31 °C, and under progressive hypoxia (PH; PO =  ~ 21 to 2.

Morphological and cardiac alterations after crude oil exposure in the early-life stages of the tropical gar (Atractosteus tropicus).

Fish development can be affected by environmental pollutants such as crude oil (anthropogenic or natural sources), causing alterations especially in cardiac function and morphology. Most such studies have focused on saltwater species, whereas studies in freshwater fishes are scant. The objective of the current study was to evaluate the effects of crude oil exposure (as 0, 5, 10, 15, or 20% high-energy water accommodated fractions, HEWAF) on cardiac function and edema formation during two early periods of development (embryo and eleuteroembryo, 48 h each) individually using the tropical gar Atractosteus tropicus as a model.

Hypoxia- and hyperoxia-related gene expression dynamics during developmental critical windows of the tropical gar Atractosteus tropicus.

Aquatic hypoxia is both a naturally-occurring and anthropogenically-generated event. Fish species have evolved different adaptations to cope with hypoxic environments, including gill modifications and air breathing. However, little is known about the molecular mechanisms involved in the respiration of embryonic and larval fishes during critical windows of development.

Expression of ion transport proteins and routine metabolism in juveniles of tropical gar (Atractosteus tropicus) exposed to ammonia.

Tropical gar (Atractosteus tropicus) thrives in aquatic habitats with high levels of total nitrogen (TAN) and unionized ammonia (NH). However, the tolerance of TAN and NH, the excretion mechanisms involved, and the effects of these chemicals on routine metabolism are still unknown. Therefore, our objectives were to assess the acute toxicity of TAN and NH in A.

Developmental changes in oxygen consumption and hypoxia tolerance in the heat and hypoxia-adapted tabasco line of the Nile tilapia Oreochromis niloticus, with a survey of the metabolic literature for the genus Oreochromis.

The genus Oreochromis is among the most popular of the tilapiine cichlid tribe for aquaculture. However, their temperature and hypoxia tolerance, if tested at all, is usually tested at temperatures of 20-25°C, rather than at the considerably higher temperatures of 30-35°C typical of tropical aquaculture. We hypothesized that both larvae and adults of the heat and hypoxia-adapted Tabasco-line of the Nile tilapia Oreochromis niloticus would be relatively hypoxia-tolerant.

Developmental cardiorespiratory physiology of the air-breathing tropical gar, Atractosteus tropicus.

The physiological transition to aerial breathing in larval air-breathing fishes is poorly understood. We investigated gill ventilation frequency (f), heart rate (f), and air breathing frequency (f) as a function of development, activity, hypoxia, and temperature in embryos/larvae from day (D) 2.5 to D30 posthatch of the tropical gar, Atractosteus tropicus, an obligate air breather.