There are so many species of fish that, if we have an aquarium at home, it is essential that we are clear about which ones coexist. This is so because fundamental aspects of the behavior of these animals will depend on the species. In this article on our site we will focus on reproduction, which can happen in different ways.
Specifically, we will give details on what is popularly known as the pregnancy in fish. We will explain what the most obvious symptoms are, the duration and the birth of the eggs or fry. Keep reading!
How do fish reproduce?
Basically in fish there are two ways of reproducing, depending on whether fertilization takes place inside or outside the body. Thus, we can classify them into the following groups:
- Oviparous fish: fertilization is external, which means that the female lays eggs and they are fertilized outside her body for the male. Depending on the species, the eggs are deposited on the bottom, float, stick to rocks or algae, shelter in nests or the fish carry them on their own body.
- Viviparous fish: their fertilization is internal, that is, the males fertilize the eggs inside the body of the females and the females give birth to the young alive.
- Ovoviviparous fish: they have another type of internal fertilization. The female, after copulating with her, carries the fertilized eggs inside her and the young mature in them. These eggs can either hatch in the body or be expelled first.
In cases where there is internal fertilization is where we could talk about pregnancy in fish In any case, to know how the fish in our aquarium, the first thing is that we are clear about what species we have in order to be able to correctly inform ourselves about their reproduction.
How to tell if a fish is male or female?
For both egg laying and pregnancy to occur in fish, it is essential that there be the presence of males and females Dada Due to the large number of fish species, there is no single rule to follow when it comes to differentiating between the sexes.
In some fish it is simple because they present what is called sexual dimorphismThis implies that males and females show physical differences that allow differentiation. For example, they have different sizes or colors or, in the case of viviparous, anal fins of different shapes. An example is sexually dimorphic betta fish, one of the most popular aquarium fish.
We also have to take into account that there are hermaphrodite fish. This means that they will be able to behave indistinctly as females or as males. In other cases, the fish is born with one sex and, as it matures, it changes to the opposite.
Pregnancy symptoms in fish
Once we have clear the characteristics of the fauna of our aquarium, we can focus on what we will call fish pregnancy. If we have males and females, the first thing that interests us is how to tell if a fish is pregnant.
Sometimes it can be complicated because, for example, if we supply too much food, a fattening specimen can look like a pregnant fish. In addition, the anatomical conformation of some species leads to confusion with pregnant fish. In others, which are oviparous, what seems to us to be a pregnancy could be a sign of disease. This would be the case, for example, of a pregnant telescope fish.
To avoid mistakes, it is important that we closely observe the fish every day. We will detect changes like the following:
- A growing lump under the abdomen.
- The lump will change shape.
- Spot in the abdominal area that corresponds to the eyes of the young in gestation. It's the pregnant spot.
We can have pregnant fish from cold water and warm water, since this reproductive option depends on the species, not on the temperature of the environment.
How long does a fish's pregnancy last?
The duration of pregnancy in fish will vary depending on the species and the living conditions. Thus, we can find cases in which in about a month the pups are already formed and can go outside. On the other hand, in other species the gestation process takes up to two months.
How do you know when a fish is going to give birth?
Although, as always, there will be differences between species, termination of pregnancy in fish can be anticipated by looking at the appearance of the lumpcontaining the eggs. When the hatchlings are about to emerge, this bulge is at its maximum size and takes on a more square shape. In the species in which abdominal spots are seen, these move towards the anal area shortly before the little ones come out.
On other occasions, especially when it is the first time a fish is pregnant, we can notice nervousness, which the animal will show swimming without stopping by the aquarium. On the contrary, just when the new fish are about to hatch, it will stay for a long time still somewhere quiet
In the following video, from the YouTube channel King Of Aqua, we can see the birth of a molly fish:
