1. Do ratfish really swim in groups?
In some aquarium literature, ratfish of the genus Corydoras (catfish), Scleleromystax, Brochis (catfish genus), and Aspidoras (genus Catfish) are generally referred to as a "swarm of fish" and it is recommended to keep at least 4-6 individuals together in the tank. But we can only see ratfish swimming in groups occasionally in fish tanks, are they really fish with group properties?
Corydoras burgessi The gills of the large red-headed rats and the golden spots on their necks allow them to remain together in the black waters.
First of all, we would at least think that 4-6 fish cannot be called a herd, because "a flock" usually feels very much in consciousness (!). And in such a group, each individual member of the group is not familiar with each other.
This will be considered a group of fish
Typical of the group animals are the purple-winged starling (Sturnus vulgaris, a very common native bird), flocks of bees, and sardines, as shown in the image below.
Purple-winged starling flocks of birds
The purple-winged starling (Sturnus vulgaris) is impressive with its spectacular group flight.
The specific characteristics of the so-called group are probably that the group of individuals in a group reflects like an individual, or an organization with a unified mind, like the flight movement of a group of purple-winged starlings or the swaming behavior of a school of sardines, which is impressively consistent! It would be interesting to delve into the mechanism of fauna sociality.
2. Swarm swimming in the fish tank
The swimming of the fish in the fish tank is almost impossible to achieve the spectacular scene of the two animals mentioned above, the only one that is more similar is the red-nosed scissors (red-headed scissors Hemigrammus bleheri). If we keep a large number of red-nosed scissors (more than 50) in a large enough tank (say, 150 cm long), then we can actually observe the swimming scenes of the fish (at least occasionally).
Red-nosed scissors lamp fish
Other fish with clusters, such as black hooks, traffic lights, and ratfish, cannot observe such scenes. In addition, even if you have 6 ratfish in your fish tank, you will rarely find them clustered together. Animals always maintain a certain distance from each other, especially the genus Catfish in ratfish is almost "isolated". So how do we define such behavioral traits? I feel that fish like this should not be called "group fish", but "group fish" or "social fish - social fish". This means that individuals between them often maintain mutually peaceful internal communication.
In fish tanks, fish usually only usually even know each other (this is almost not the case in nature). The truth is that these fish usually exhibit obvious ostentatious behavior when cared for alone, which is why we strongly recommend keeping 4 to 6 animals of about 4 to 6 sizes.
It should also be noted that there are many fingerlings that can only be kept with the same species, and there are some fish species that are "loners" who cannot tolerate any other fish species, except that they will need another alien mate when breeding.
3. How colucent are ratfish?
Indeed, several species of ratfish species have been found swimming in natural waters, such as hundreds or even a thousand individuals on a scale. These fish are frequently and cheaply caught and traded, and the grouping together makes them particularly easy to catch in large quantities.
Crown leopard rat swarm from Orinoco Orinoco River (Venezuela).
Unfortunately, the ratfish that were caught could only observe swarm behavior in the aquarium for a few days. For a limited period of a few days, they actually swim in groups like an organization, like an individual's performance, very consistent. However, this is actually the case because every member of the group is mimicking the behavior of a neighboring fish. They swim in groups to avoid predator attacks and protect themselves, and relatively speaking, the drawbacks of group behavior are also very obvious, that is, they must share food with individuals in the group. Once they settle down and realize that there is no serious danger in the tank, they quickly abandon the act of swarming. This is why the ratfish in the fish tank quickly separated and moved their own actions.
Ambica rat herd from Peru (Corydoras ambiacus).
This population trait of ratfish clearly has a positive effect, and when they realize that it is necessary to form a group, they can form a group at any time, which can give the fish a sense of security, thereby increasing the health level of the fish. Since ratfish may not have known other individuals before, it is generally sufficient to have 4-6 specimens in the tank.
Indian rats swim in groups only when they have just been caught in a fish tank
4. In short, the ratfish swarm does exist!
It's just that only a very small number of people can really observe the real swarm behavior of the rat fish in the fish tank, and those lucky guys who are responsible for taking care of the fish in a relatively short period of time during the fishing import and export process!
Author: Frank Schäfer, a biologist born in 1964, has been an avid animal and plant breeder since childhood. From an early age he was particularly interested in fish and was also fascinated by reptiles, amphibians, invertebrates, small mammals and birds, as well as a wide variety of plants.
Fish water circle translation, if you need to reprint, please indicate the source of the fish water circle.
Source: Fish Hydrosphere