Tunas have scales that are rudimentary and located beneath the skin. This makes it difficult for them to be spotted with bare eyes.
Types of fish with no scales
These have none: catfish, rays, sharks, chimeras, moray eels, paddlefishes, sturgeons, sailfin blennies, lampreys, and the cambooth blennies. However, most of them have known other scale alternatives. For instance, the sturgeons have scutes in place of scales. Other fish species with no scales have denticles that are like tiny teeth, which makes their skin feel like sandpaper.
Tuna is a type of fish that is mostly found in salty water. Also known as a tunny, it belongs to the Thunnin tribe and the Scombridae family. Looking at their characteristics, they have the most streamlined bodies, quite robust and elongated.
Also, their bodies are rounded and with a tail base that is slender. Their keel, on the other hand, is very conspicuous found on both sides of the tail base, very elaborate scales at the shoulder location, and a number of tiny finlets just behind the anal fins and the dorsal part.
They have a network of blood vessels just under their skin that works to regulate the temperature of the tuna fish. This makes these water animals be unique when it comes to maintaining their temperature, having it higher compared to the water body. In most cases, they have their temperature from around 5 to 12 degrees higher than the surrounding water. Other muscles may go up to 21 degrees.
Where Can You Find Tuna Fish
Tuna Fish is known for traveling through a wide range of miles in the ocean waters. This makes them available in over 70 countries, according to the National Fisheries Institute. This ranges from Mexico, Europe, Ghana, Japan, United States, France, Ecuador to the Philippines, amongst others.
The Pacific Ocean is known to produce the highest amount of tuna fish that amounts to 2.3 million tons, as per the NFI. This sums up to 66 percent of all the amount of fish caught around the globe. The rest of the tuna fish caught is from the Indian ocean with 20.7 percent, the Atlantic Ocean with 12.5 percent, and the Black Sea and the Mediterranean Sea with 0.8 percent, according to the National Fisheries Institute statistics.
Types of Tuna Fish
There are many types of Tuna fish, but when it comes to commercial consumption, there are five species that take center stage. We analyze them below.
It’s also known as Ahi in some areas like Hawaii. The Bigeye tuna love swimming in the deep waters at mostly 900 to 1200 feet. Its flavor is very mild and not known to be canned. This tuna fish species are found in all waters but the Mediterranean sea. It can be found in a length of between 1-7 ft and is known to feed on cephalopods and other fish varieties.
The largest Bigeye Tuna to ever be caught in the Atlantic Ocean weighed 392 pounds.
This type of tuna fish mostly comes in pouches or cans. It’s also known as white tuna and the only one with those referrals on the can in the United States. This makes it a premium variety amongst canned tuna as it contains white flesh, which can be sometimes pinkish and has a mild flavor. It’s also a good source of Omega 3 oils.
Because of their migratory nature, they are found in the Pacific, Atlantic, and Mediterranean oceans. Those from the Pacific are, however, make good canned tuna. This tuna species can be as heavy as 88 pounds and go all the way to 4.2 feet. In the Mediterranean, the Albacore tuna can live up to 9 years, while it extends to 13 years long in the Atlantic.
Their diet is mainly the squid, crustaceans, and other smaller fish.
A female Albacore that weighs 44 pounds can produce up to 3 million eggs in one season.
This is popular when it comes to making sushi. Its, however, is not recommended for canned tuna. The bluefish tuna is also known to be the fattiest and darkest among the tuna species. Further still, it is the largest compared to other commercial tuna fish that are caught. It can weigh up to 1000 pounds. The flavor of the Bluefin tuna transforms from mild to very elaborate as it ages.
Being high migrators, they can be found in almost all oceans. They have a long lifespan of up to 30 years. Their length can go all the way to 12 feet and weigh up to 1200 pounds. Their food entails squid, pelagic red crab, krill, and smaller fish.
Their popularity stems from their taste to size and the fact that they are good for making sashimi. They also rarely reproduce, which has led to overfishing of its kind. However, there are regulations that have been set by the relevant authorities to ensure they are not lost forever.
It has almost the same similarities with the Bigeye tuna as it’s also called the “ahi.” However, this is popularly referred to as pouched tuna or “light” canned. Its color is more of oink and has a deeper taste compared to the Albacore tuna.
They can be found in both the subtropical and tropical waters and mostly take the warm waters on the surface of the ocean. The yellowfin tuna mostly feed on squid, crustaceans, and other smaller fish. They weigh all the way to 440 pounds and can get to 7 feet in length.
In the United States, you’ll mostly find the Skipjack tuna as pouched or canned tuna. Its nutrients entail zinc, iron, Vitamins D and B12, selenium, phosphorus, magnesium, and omega-three oils.
They mostly prefer the warm surface water but could dive to 850 feet during the daytime. The skipjack tuna mostly feed on crustaceans, mollusks, cephalopods, and other smaller fish.
Is Tuna Unclean?
Tuna is considered to be unclean because they have no scales. They are only known to have minimal scales at the side of their head and some underneath their skin. The rudimentary scales are quite underdeveloped, leaving the tuna with a smooth skin that renders them unclean.