Caribbean Sharpnose Puffer Canthigaster rostrata
Species ID: T.CR
Description: A small, roughly football-shaped fish with a large pointed snout, small fins at the rear of the body, and a prominent tail. The sides of the body vary from pale yellow to white with bright blue spots, while the edges of the tail fin have thick, dark borders that distinguish this species from similar puffers. The back is typically brown in females and grey in mature males
Maximum Size: 12 cm (4.5 in)
Longevity: Unknown; but may up to 10 years based on the longevity of related species
Status: Not currently on the IUCN endangered species list
Caribbean Sharpnose Puffers & People: This puffer is not caught as a food fish, but because of its small size and bright colours it is widely collected for the aquarium trade
Geographical Range: Found throughout the shallow waters of the Caribbean
Coral Reef Zone: Found in the back reef, reef flat, and fore reef zones
Favourite Habitat: Found in most areas of the reef, especially in areas where gorgonians are common. May also inhabit seagrass beds
Depth Range: 1–40 m (3–130 ft)
A Day in the Life:
Dawn: Spawning occurs following sunrise
Day: Puffers forage and defend territories
Dusk: Puffers seek shelter for the night
Night: Sharpnose puffers rest within the reef
Who Eats Who
Sharpnose puffers are omnivores that consume small reef invertebrates, such as crabs, shrimps, polychaete worms, and snails; they may also graze on sponges, algae, and seagrass. These fish, like other puffers, possess tetrodotoxin which makes them poisonous to eat. As such, most reef predators avoid them. However, they are still occasionally consumed by groupers, snappers, barracuda and eels.
Scuba Diver & Snorkeler Best Practices
Refrain from feeding marine life : Coral reef organisms should never be fed. Although this may seem like a harmless practice that allows you to get close to your favourite organisms, it actually disturbs normal feeding patterns and diets. Scientists have documented turtles being fed bread, dog food and even cheese—none of these foods are found naturally in the marine environment, and they can cause untold stress to the organisms that consume them. Conditioning wild animals to become comfortable with hand-feeding by humans alters their behaviour and makes them more vulnerable to capture, which directly affects their survival—this is particularly a concern for endangered sea turtles.
Sharpnose puffers are relatively easy to approach if divers and snorkelers move slowly and regulate their breathing.
Sharpnose puffers are omnivorous fish that actively search the reef for food, including small crabs, shrimps and worms, during the daytime. They can be seen picking at invertebrates or algae growing on the substrate or nibbling on seagrasses.
Observe, record & share:
O T.CR-101 – Feeding on invertebrates: Sharpnose puffers pick invertebrates off the reef
O T.CR-102 – Grazing: Sharpnose puffers nibble on algae or seagrass
Attack & Defense Behaviour
Sharpnose puffers are territorial and coexist with other sharpnose puffers in a complex social hierarchy. Females defend a small, permanent territory, whereas males defend a larger territory that encompasses the territories of several females that are part of their harem. Sharpnose puffers know the territorial boundaries of their neighbours intimately. If they must cross into the territory of a neighbour, they adopt a precautionary mottled colour pattern that is thought to help camouflage them from the territory owner, as well as indicate submission if sighted. If intruders are caught they are met with a series of aggressive displays, such as tilting the body forward and presenting the flank. If this display does not deter an intruder, the defending puffer will face the threat head-on with the fins spread, and flex the body to make it appear thicker. If the opponent relents, it will leave while adopting a submissive display where the belly is flattened to make the fish appear smaller. If the opponent persists, then the fish may circle each other and attempt to bite. The sharpnose puffer’s primary defence against predation is to retreat into a reef recess; however as a last resort puffers can inflate to increase their size, making them harder to swallow.
Observe, record & share:
O T.CR-201 – Mottled colouration: Intruding fish adopt a mottled colour pattern
O T.CR-202 – Tilting display: Sharpnose puffers tilt forward and present their flank
O T.CR-203 – Frontal display: Puffers face the threat head-on with fins spread, flexing the body to make it appear thicker
O T.CR-204 – Submissive display: Puffers flatten the belly to appear smaller and adopt a mottled colour pattern
O T.CR-205 – Circling: Puffers chase each other in a tight circle
O T.CR-206 – Biting: Puffers will try to bite each other
O T.CR-207 – Inflation: Puffers under extreme stress may puff up their bellies to become too large to swallow
Sharpnose puffers reproduce sexually by laying demersal eggs and do not undergo sex change during reproductive development. Males regularly visit the female members of their harem throughout the day to reinforce their bond. During the breeding season, these visits often result in spawning when they occur in the early morning hours. Males enter a female’s territory, spread their fins and present their flank. Females respond with a submissive display, and the pair spends a few minutes feeding side by side. If the female is ready to spawn, she will search the substrate for a patch of algae to use as a nest and will spend some time cleaning it while the male encourages her by nudging her repeatedly with his snout. If the female stops preparing the nest, or attempts to leave, the male often becomes aggressive and may display or even bite to urge her on. Once the nest is ready, the couple swim side by side just above it. The female lays her eggs into the nest and the male fertilizes them immediately. Once the eggs are laid, the two sharpnose puffers return to their daily activities and the nest is left uncared for until the eggs hatch and disperse into the plankton. Sharpnose puffers have been observed mating in the spring, but the full extent of their breeding season is currently unknown.
Observe, record & share:
O T.CR-301 – Visiting: Males enter a female’s territory, spread their fins and present their flank. Females respond with a submissive display
O T.CR-302 – Nest preparation: Females choose a patch of algae as a nest and clean it
O T.CR-303 – Nudging: Males nudge females with their snout to encourage them
O T.CR-304 – Male aggression: If a female attempts to break off spawning, she is chased and bitten by the male
O T.CR-305 – Spawning: The male and female hover together just above the prepared nest and spawn
Mottled colouration: Caribbean sharpnose puffers aggressively defend the boundaries to their territory. In densely populated areas an entire reef might be carved up into a territorial mosaic. Males that wish to leave their territory may have to pass through a neighbour’s territory, resulting in confrontation. In order to reduce their odds of being attacked, wandering males adopt a special submissive, mottled colour pattern, making them harder to spot. Even when spotted, this pattern is believed to help curb the aggression of resident males because they are acknowledged as being superior.
Did You Know?
• Although most males guard a harem of females, bachelor males also exist who sneak into the harems of other males and mate with their females.
• The Caribbean sharpnose puffer, and other puffers, often feed on hard-shelled prey, which can wear down their beak-like teeth. If hard-shelled prey were to become scarce, their teeth would overgrow in much the same way a rabbit’s teeth. This is often the case with pet puffers that are improperly fed in home aquaria
What to do?
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- Order Tetraodontidae
- Length 12 cm (4.5 in)
- Weight Not recorded
- Depth 1–40 m (3–130 ft)
- Habitat Found in the back reef, reef flats and fore reef zones
- Distribution Found throughout the shallow waters of the Caribbean