The Larger The Bottom Of The Aquarium

2023 Author: Molly Page | [email protected]. Last modified: 2023-11-27 22:49

It is known that sturgeon juveniles are typical benthivores. With the help of the organs of touch and taste, she constantly seeks out food at the bottom.

In sturgeon hatcheries, juveniles are raised in pools at a very high stocking density. Rather tense competitive relations arise between individuals for access to food at the bottom. Therefore, the area of the bottom or other substrate where the juveniles feed is important.

We carried out two experiments, the purpose of which was to find out the characteristics of the behavior and competitive relations of these fish, as well as their growth rate depending on the size of the forage area.

In the first experiment, we studied juveniles of stellate sturgeon (Acipenser stellatus), in the second, Russian sturgeon (Acipenser gueldenstaedtii).

The fish were divided into two groups and placed in aquariums with feeding areas of different sizes. The rest of the keeping conditions (amount of food, water temperature, etc.) were the same.

Sevryuzhat were raised for three months in aquariums of the same volume, but the bottom area of one of them was half that of the other.

The experiment with sturgeon lasted longer - five months. The fish were kept in aquariums of equal volume, but in one of them a special device, like a stack, was installed, which made it possible to triple the size of the feeding area.

During the experiment, control weighing and measurements of the fish were carried out at regular intervals. In addition, we observed their behavior - we determined how long individual individuals swim in the immediate vicinity of the bottom or "whatnot", and also counted the number of their collisions with other members of the group.

As observations have shown, fish spend a significant part of the time at the bottom, and juveniles raised in an aquarium with a smaller feeding area do not stay there for so long. This was noted not only during meals, but also at other times.

Russian sturgeon juveniles at a fish farm

The number of collisions between fish also largely depended on the size of the food area. Feeding and well-fed fish in aquariums with smaller forage areas encountered much more frequent encounters. It also turned out that larger individuals spend much more time on the bottom than smaller ones, and this was observed primarily in smaller feeding areas.

Measurements of the length and weight of the fish showed that the growth and weight gain of juveniles also depends on the size of the food area in the aquarium. So, if the stellate sturgeon contained in a container with a larger bottom area, the weight gain averaged 3 grams, then in juveniles from the second aquarium - only 0.3; sturgeons from an aquarium with a shelf - almost 10 grams, without it - only 6.

The data obtained on the higher growth rate of experimental fish in large feeding areas indicate the exceptional importance of this factor in the artificial rearing of sturgeon.

Related article Measuring and calculating aquarium volumes

When juveniles rush to the bottom or other substrate, an increased density of fish forms in the bottom layers of the aquariums, leading to a large number of collisions. As a result, larger, stronger, calm individuals displace the weak and nervous into the middle and upper layers of the water. Therefore, in the group, two categories of fish are formed - one that stays on the substrate most of the time, and the other, which is forced to actively move in the water column. The first category is in an advantageous position - it is well supplied with food, the second is isolated from the fodder substrate and food is less accessible to it. This, as well as the possible increased energy consumption during active movement in the water column, leads to a progressive lag in the growth of fish of the second category.

A similar stratification of individuals reared with increased tension in competitive relationships is also known for fish of other species. Interestingly, in this case, this occurs while maintaining neutral intraspecific contacts characteristic of juvenile sturgeon and in the absence of specialized aggressive acts. Therefore, the relationship that develops among sturgeon juveniles under conditions of competition for access to food can be called pseudo-hierarchical.

The creation of an additional substrate, and hence an increase in the size of the forage areas, can increase the efficiency of sturgeon rearing in conditions of limited volume.

Source: Y. Sbikin, S. Budaev, N. Bibikov, magazine "Aquarium", 1994 - 2