Achirus.sp - Soles in Aquariums

Achirus achirus, Achirus fasciatus, freshwater flounder, drab sole, lined sole or how to call them ?

Flatfish are known to us mostly just from the sea. Years ago I was very surprised to discover sole like fishs at my aquarium fish dealer, too. I could not overcome the temptation at that time and took some of the animals. Unfortunately, there were very few hints about these fish in the aquarium literature. Sterba describes a genius of dwarf flounders called Achirus fasciatus or lined soles, which seems to be very similar to my fishes. There was also an article in the german Datz reporting about freshwater flounders, but the scientific name was left open, Achirus Achirus or Achirus fasciatus. Having these fish maintained some years now, I can say that they can be kept very good in a freshwater aquarium.

My soles have a flattened, asymmetrical body shape typical for flatfish. In adaptation to the living at the soil life the eyes are shifting to the left side of the body and the mouth is developing asymmetricly in youth stage. The body of the fish is oval elongated, with a well defined tail fin. The eyes stick clearly out of the head. If the sole is buried in the sand they are usually the only thing that is visible. The eyes are not completely symmetrical configured, but the right one is more forward and the left one is more backwards adjusted. The venter of the flounder is more or less white. The upper surface varies according to mood, background or simply between the individual animals. Mostly the fish have a sand-colored base color and dark brown, irregular spots. Some of them are quite dark. Very characteristic is the stocking with small hairs on the top.

The distribution of soles is focused on the east coast of the United States, Florida and Texas. There they live in freshwater as well as in seawater. Another genius, Achirus Achirus, the Drab Sole, lives in the pure fresh water of the Amazon. As I have not known exactly what water parameters are preferred by my soles, I maintain them for the last few years in pure freshwater. This caging seem to be very good for them, as they eat and have clearly increased in size. The biggest sole that I'm keeping is about 3 inches long.

I've co-housed the animals in the youth stage in a 30 liter aquarium with Red Cherry Shrimps of the genus Neocaridina. This tank was used again and again as rearing aquarium for several lifebearer and killifishes. As far as I could see, there was never a missing juvenile fish. Even with two young the Ancistrus catfish they were on good terms. With increasing size, the soles have been put in a 160 liter tank sharing it with Corydoras catfish and various killies.

Sterba reported that these soils are nocturnal. I can not agree with this opinion, because my soles are active during the day. I wouldn't call them vivid, but they are often seen during the day exploring the basin. Half-buried in sand or attached to the aquarium glass, it is always interesting to observe them.

For feeding live food or frozen food is willingly taken. Especially all types of mosquito larvae are very well suited. After an extensive feeding with red mosquito larvae they have some similarity to pufferfish.

I have never seen them eating flake food, but frozen food every 2 to 3 days seems to fully satisfy them. However, I could not observe a chasing of living food. The soles are probably lurking predators, half-buried in the sand waiting for goods passing by. At best the food is falling directly in front of their head. Therefore they should not be co-housed with too greedy and fast-eating fish, because otherwise they will get not enought food. It's also a good way to saturate the other fish with flake food and feeding thereafter the soles with frozen or live food. Soles

The fish dig themselfs in a few seconds in case of danger, so that only their eyes are sticking out. For such actions, the flounder can also go out of the water fast, so it is better to scare them not to much in open tanks.

I think it's become clear that although I do not know exactly which soles I actually maintaine it makes a tremendous fun keeping this unusual fish. I tend to call them Achirus achirus, the drab sole.