Under the Sea Part I: Fish
"Roughly 200,000 salmon or red coloured eggs are released at one time. Four and a half days after fertilisation the eggs turn green with a red yolk. The male sergeant major guards the eggs and turns blue in the process..."
We’ve been lucky enough to enjoy some incredible snorkelling in Curação. In this particularly hot el niño year, it has been wonderful to have the opportunity to cool down a bit and observe the slower pace of life under the water. This week I’ve taken the time to research some cool facts about some of the fish we’ve seen. They are very different from mammals, so enjoy. Lots of them change sex and colour. Next week I’ll write about corals.
We’ve seen a lot of Parrotfish while snorkelling in the Caribbean. They are large and colourful, so easily spotted. They look like they have a beak, which is where they get their name from along with their bright colours. They feed on coral polyps with their fused teeth. They usually have a moderately beneficial environmental effect by weakening the coral so it breaks off and propagates elsewhere. They often carry parasites, which are fed on by smaller fish, such as wrasse.
The photographs below both show Stoplight Parrotfish, but they are completely different colours. This is because the bluish one with the yellow ‘stoplight’ on its tail is a ‘secondary male.’ This coloured fish was born female, but became male, which is a common occurrence when population numbers are low.
The fins of the Palometa are striking. It is carnivorous, eating worms, insect pupae, and smaller fish
The Smooth Trunkfish is a type of boxfish. It is shaped a bit like a triangular prism with the pointed edge at the top and a flat base. Its mouth looks like it is always pouting, but this is because it shoots a jet of water to blow the sand off small molluscs, worms, crustaceans and sponges. This morning I watched one shoot its jet at some cat food I had thrown overboard. It used it to blow the cat biscuit up into smaller pieces so it could eat it. They are usually found alone.
The Sergeant Major is named for the five vertical stripes on its silver body that are reminiscent of military stripes. The top of the fish is yellow. When it is hiding it goes into camouflage mode, with its body changing to dark grey. When snorkelling they seem more confident than lots of other fish, swimming curiously towards you, possibly as their small size means they are not a target of fishing. They usually swim in schools and are active in the daytime and seek shelter at night. They are omnivorous, eating algae and small crustaceans, such as shrimp and fish. Spawning occurs on rocks, shipwrecks and reefs. Males build nests and pursue the females in the early morning hours. Roughly 200,000 salmon or red coloured eggs are released at one time. Four and a half days after fertilisation the eggs turn green with a red yolk. The male sergeant major guards the eggs and turns blue in the process. The eggs hatch roughly six and a half days after fertilisation.
Atlantic or Caribbean Blue Tang
There are more than eighty varieties of Tang, which are a type of surgeonfish, which get their name from the sharp spines on either side of their tail. Most species are herbivores, feeding primarily on benthic algae including brown, red, green and blue-green, and less often on seagrass. However, as adolescents they will also eat parasites from the flippers of Green Turtles. Juveniles spend their time alone and adults may form shoals of up to ten fish, although the shoal below is larger than that.
The Bluehead Wrasse is very striking to look at despite its small size. It (surprise!) has a blue head, followed by a black band, a white band, another black band and the rest of the body is yellowish green with a blue tail. They eat a range of small invertebrates and crustaceans as well as parasites on the bodies of other fish and zooplankton. They are also prey for many other larger fish. All bluehead wrasse are born female with some becoming male as they mature. Bluehead wrasse may reproduce both as a female and male during their lifetime.
The Bambi of the sea, these fish have huge eyes. Despite being a larger fish, they are very well defended as they can blow up into a balloon shape by swallowing water and are covered in spines and they have a neurotoxin and they like to spend a lot of time hiding under reefs. They are also nocturnal. Perhaps it’s because they are solitary fish so don’t have the safety of a shoal.
We’ve seen loads of these fish hanging out in huge shoals drifting underneath reef overhangs. They are very pretty with a yellow horizontal band across their middle and a yellow tail. They are prey to larger fish, such as barracudas and sharks. Sadly they are also at risk of being kidnapped for captivity in aquariums (like many of the other fish mentioned), and are overfished in many places, such as Brazil and Mexico. As a result there are sickening moves to farm them. Farming is a so-called response to overfishing. Fish farming leads to stress, injuries, disease and parasites, which are widely treated with antibiotics, which leads to drug-resistance. Fish that escape these farms often go on to spread disease in the wild populations. It is an established scientific fact that fish feel pain and farmed fish are often starved for several days before being killed. Methods of slaughter include bleeding out, being hit on the head repeatedly, suffocating or freezing. The only way to ensure sustainability in fish populations is not to eat them at all.
Here in the Caribbean Sea these fish have the space to swim freely, participate in their normal social groupings, such as shoals, or exhibit other natural symbiotic behaviours, such as cleaning parasites from other species and maintaining the ecosystem of the ocean. They reproduce and hide from their prey in reefs or rocks. Their health and happiness is not conducive to living captive in a tank or aquarium, where they will suffer pain and stress due to having inadequate space, the wrong temperature tank, an unstimulating environment and being housed with other fish that have been chosen for their looks rather than their natural behaviours. I strongly urge people not to keep fish in a home tank or visit aquariums and therefore fund this cruelty. They are beautiful and fascinating creatures, which we still have so much to learn about. The best way to appreciate them is through watching documentaries, such as Blue Planet or observing them in the wild by snorkelling or diving.
“Abudefduf Saxatilis.” Discover Fishes, www.floridamuseum.ufl.edu/discover-fish/species-profiles/abudefduf-saxatilis.
Oceana. “Bluehead Wrasse - Oceana.” Oceana, 18 May 2023, oceana.org/marine-life/bluehead-wrasse.
Simon. “Blue Tang Surgeonfish | Animal-World.” Animal-World, 18 Aug. 2023, animal-world.com/caribblue.
Tannen, Janette Neuwahl. Researchers Work to Find Strategies to Produce Seafood. 5 Sept. 2023, news.miami.edu/rosenstiel/stories/2021/09/aquaculture-researchers-work-to-find-strategies-to-produce-seafood.html.
Wikipedia contributors. “Smooth Trunkfish.” Wikipedia, Jan. 2023, en.wikipedia.org/wiki/Smooth_trunkfish.
---. “Spot-fin Porcupinefish.” Wikipedia, June 2023, en.wikipedia.org/wiki/Spot-fin_porcupinefish.
---. “Trachinotus Goodei.” Wikipedia, May 2023, en.wikipedia.org/wiki/Trachinotus_goodei.
---. “Yellowtail Snapper.” Wikipedia, May 2023, en.wikipedia.org/wiki/Yellowtail_snapper.
You can find our PODCAST episodes at the links below
YOUTUBE (for video version)