▷ Zebrafish in the Aquarium | All information and details

Data sheet zebrafish

German name:
zebrafish

Scientific name:
Brachydanio rerio

Origin:
India, Pakistan

Size:
Body length up to 8 cm

Aquarium

Length:
Length from 80 cm width, pelvis stretched as long as possible

Contents:
from 100 liters

water values

Temperature:
20°- 26° C

pH:
6 – 8

GH:
5° – 25° dH

Behave

Area:
middle area

Lining:
Omnivores (live food, frozen food, dry food), also vegetable food

Behave:
very lively, peaceful

Number:
Schooling fish, groups of at least 7 animals

Difficulty level:
Beginner

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Behavior of zebrafish

Zebrafish, Brachydanio rerio, are native to the Ganges tributaries in northern India, Bangladesh and Pakistan. There they live in stagnant or slow-flowing water, for example in rice fields.

In the aquarium they like to swim together in groups of 2 or 3 fish. Sometimes larger groups form. Sometimes they also swim individually through the aquarium.

A typical shoal that behaves like a single fish is rarely formed. At least 7 zebrafish should be kept together.

aggressiveness of zebra barbs

Zebrafish with veil fins Source: Image on Wikimedia Commons License: Public domain Author: Marrabbio2

Zebra barbs are among the danios that are sometimes assumed to be aggressive. According to a typical account, a female became so aggressive towards the males that one male had to be isolated because of bite wounds. The total of 6 danios were kept in a 60 liter aquarium with many plants, stones and coconuts as hiding places. However, zebrafish do not usually hide in caves. They may swim in briefly, but immediately out again. In the aquarium there were also two sucking loaches measuring 6 centimeters in size, which were also aggressive towards each other.

A 60 liter aquarium is too small for the fast and persistently swimming zebrafish, even if such a tank is often given as the minimum size. Nevertheless, it is doubtful whether the male was really bitten and injured by the female.

It is usually not a cause for concern when zebrafish are chasing and shooing each other. This is completely normal. However, they should not be kept with fish that cannot tolerate the stress.

Over time, zebrafish also become a little calmer. When they are in the mood to spawn, however, they become really active again. They come in spawning mood about every 4 – 6 weeks.

gender differences

The basic color, on which the dark blue to black longitudinal stripes lie, is golden yellow in sexually mature males and silver to white in females.

The males are significantly slimmer than the females. The females are plump and can become extremely fat at times. Sometimes such fat females spawn immediately if they are placed in a separate tank. They may be disturbed too much in the community tank. In order for the eggs to be fertilized, a male must be added.

Breeding of zebrafish

Zebrafish Source: Image on Wikimedia Commons License: Public domain Author: Azul

The parents are initially well fed, mainly with mosquito larvae. They can stay in the normal aquarium. It is best not to change the water for a week and to feed them well during this time.

A small vessel or aquarium is filled with fresh tap water. A container with 5 liters of water is enough. Of course bigger is better. The water should stand for 2 days. Then some delicate plants are placed in the vessel. The plants are weighed down in such a way that they sink to the ground. A bush of fine plants can e.g. B. be attached to a stone with a rubber. An air-powered sponge filter is used as the filter. A heating rod keeps the temperature at 24° to 25° C. The pool can be placed on a windowsill so that the morning sun shines on the pool. However, morning sun is not absolutely necessary.

The parents eat the spawn and the young. A spawning grate or shooter can be placed in the spawning tank to cover the ground as protection.

In the late afternoon the danios are fed well again. Then a pair of zebrafish is placed in the spawning pool. 2-3 females and 3-5 males can also be placed in somewhat larger spawning tanks. The spawning tank must be well covered.

The next morning the rasbora begin to sprout and spawn on a clump of plants. The eggs do not stick and fall through any spawning grid that may be present. The eggs are about 1 mm thick and almost invisible.

You can see the eggs best if you shine a flashlight at an angle in the dark or if you look at them on a dark background.

The next day around noon the fish are taken out of the tank. Heater and filter are also removed. The water is briefly whirled up by stirring. When the eggs are back on the ground, but the dirt, fish droppings, etc. are still floating, the dirty water is poured off except for a small residue. Water is then topped up and ventilation and heating are put back into operation. The pool is slightly darkened.

After a day, you can see the eyes of the young and they move in the eggs. At 25° C the larvae hatch after 1.5 – 2 days. Once the larvae hatch, it takes a few more days for the young to swim freely.

Breeding in the community tank

If there is a lot of java moss in a community tank, a few young can occasionally grow up in the community tank as well. With an internal filter, a nylon stocking should be pulled over the filter as protection so that the young are not pulled into the filter.

rearing

After free swimming, they are fed sparingly with dust-fine flake food. The water must be changed carefully as often as possible without sucking off the fish. Because the young grow very quickly, the problem quickly disappears.

The young are best raised in a larger tank. Otherwise they grow at different rates. A larger pool is also easier to clean. Also, such an approach can result in a few hundred boys, most of whom make it through.

It does not necessarily have to be fed with protozoa. Dust food or freshly hatched artemia can also be fed.

Barbel like to grow in spurts. So it can happen that after a few weeks the young stop growing for a while despite being well fed. Factors that limit growth are otherwise the water quality and the food supply or the quality of the food.

Zebrafish with gill damage may be overbred.

Some seemingly overbred zebrafish have one or two swollen, red gills that appear to be protruding. One or both gill covers are missing. These animals have a shorter lifespan than those with complete operculums. Otherwise they are just as lively as other zebrafish.

Zebrafish and leopardfish can be kept together.

Zebrafish, Brachydanio rerio, can be kept together with Leopardfish, Brachydanio frankei. Leopard danios are believed to be a special variation of zebra danios.

FAQs – Frequently asked questions about zebrafish