Fish are an important source of food for many people around the world. There are estimated to be over 100 million tons of fish stocked in water bodies around the world. That’s a lot of fish! Unfortunately, fish can become an endangered species if not handled properly. In this article, we will discuss some essential facts about fish reproduction that you need to know.
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When Do Fish Reproduct?
Fish are living creatures and as such, they require certain environmental factors in order to thrive. Generally speaking, fish are born approximately every two years and begin reproducing at a very young age. They can continue to reproduce for the rest of their lives.
Certainty of spawning and hatching can be increased by maintaining a constant temperature (77-78 degrees Fahrenheit) and dissolved oxygen content in the water. If these two factors are taken care of, the fish will spawn more often and larger eggs will be produced. In poor water conditions, the fish may not be able to reproduce at all!
How Long Does It Take Fish To Reach Maturity?
Fish reach maturity at different times, depending on the size of the fish. Smaller fish usually mature faster than larger fish. One of the most commonly used terms in regards to fish maturity is “size at hatching” (SAH). Smaller fish with an SAH of 3 inches or less are usually considered immature and should not be caught or handled by anyone except the parent fish.
Larger fish with an SAH of more than 3 inches are usually caught at a certain age and should not be eaten by anyone. Most large fish will begin maturing at an SAH of 5 inches or more. Depending on the species, fish will mature at several different sizes. Having said that, here are the approximate maturation times for some popular fish species:
- Aberdeen Angus
- Argentine Sea Bass
- Atlantic Salmon
- Barramundi
- Bluefish
- Carp
- Caviar
- Chilean Sea Bass
- Cod
- Dolphinfish
- Flounder
- Gadiformes
- Halibut
- King Mackerel
- Langoustes
- Larvae (juvenile stage)
- Moray Eel
- Oyster
- Permit
- Pike
- Shark
- Snapper
- Squid
- Surface-Rising Fish
- Troll
- Whiting
- Winter Flounder
- Yellowtail
- Dalmatian Dogfish
When Do Fish Become Mature?
Once fish reach maturity, they are considered adults and can reproduce as many times as necessary. This is mainly dependent on the species in question. Some fish, such as the platypus and eel, are born with the ability to reproduce and don’t require mating for reproduction to take place. In other species, such as the carp and salmon, the fish must mate with another individual of the same species in order to produce offspring. This is called “pair bonding” and determines the length of time the fish stay together as a pair before spawning takes place.
How Many Eggs Does A Fish Egg Have?
Fish eggs come in all shapes and sizes, which determines how many eggs they contain. The average fish egg contains 16 million sperm. This is one of the primary reasons why multiple-egg laying species are considered “superior” in comparison to single-egg layers. Some fish lay eggs that are only a few cells in size with the hope that the resulting offspring will be able to feed themselves without any assistance. These types of fish are considered “semiautonomous” because they are capable of reproducing without any external stimulation.
The above image is a graphical representation of a typical fish egg. The yolk is at the center with a thick white ring separating the yolk from the white. The top of the egg is also referred to as the “chick hood” due to its bright color and its function as a protective covering for the developing embryo. Most fish will eat any meat that is not their own and so the hood provides a protective covering for the developing embryo while it feeds on the yolk sac which is rich in nutrients.
How Long Does It Take Fish To Hatch?
The hatching process of a fish is rather complex and can involve several hours or even days. The temperature of the water and dissolved oxygen content are vital factors which help determine how fast the fish will hatch. The majority of freshwater fish will start hatching at an ambient temperature of around 77 degrees Fahrenheit. It’s best to keep the water at this temperature by using an aquarium heater with thermostat control. Too high of a temperature and the eggs will not hatch properly!
Some fish, such as cod, are cold-blooded and so their hatching rate will decrease as the temperature drops. Once the eggs have hatched, the time it takes for the fish to emerge depends on several factors. One of the most important is the size of the fish. The larger the fish, the longer it will take for the larvae to complete their transformation from eggs to adults and be able to feed on larger organisms. The larger the fish, the longer it takes for the fish to reach maturity and be able to reproduce!
How Many Young Does A Female Fish Have?
After spawning, the female fish will have several eggs which she will guard carefully until the larvae begin hatching. The female may lay up to four or five clutches of eggs annually and so she will have several young at any given time. Some female fish, such as cod, are known to protect and guard their eggs for up to six months before spawning takes place. This is why the cod is considered a “lifer” because the adult life span of a cod is much longer than most other freshwater fish. The female may continue to lay eggs even after she has died due to old age or disease. This is why her lifetime is often referred to as “biennial”!
How Many Eggs Does A Male Fish Have?
The male fish usually have a larger gonad size than the female and so they are considered “dominant” in nature. Dominant male fish are typically considered “masculine” while submissive males are usually characterized as “feminine”. The male is primarily responsible for fertilizing the eggs and so he has a greater need for oxygen than the female. This is why the male tends to stay shallow while the female tends to stay deeper in the water when searching for food. Some male fish, such as the carp and goldfish, are hermaphrodites and so they will have the ability to fertilize eggs as well as provide sperm for reproduction.
The above image is a graphical representation of a male fish’s gonad. The larger the testes, the greater the ability of the fish to sire offspring. The male fish’s testes are located inside the abdominal cavity behind the stomach and intestines and to the side of the spine. When the male fish is mating, the gonads will expand and rise above the surface of the water. This is why it’s important to check for the presence of a mating head when examining a male fish’s gonads!
With so much information about fish reproduction, knowing when and how to properly handle a fish is now a lot easier. Throwing a hook in the water and hoping that a fish will bite is not a wise idea; rather, it can put the fish in danger. Knowing how long each stage of reproduction takes and when they occur can help you better understand the life cycle of the fish and how you can help them thrive in your tank!