Fish position in the aquarium

[anewbie]

As a few of you might or might not know i have some larger aquariums ranging from 12ftx4ft to 20inchx10inch. For the small aquariums this is not relevant but for the larger aquariums one thing I noticed is that fishes seem to have their favorite spot esp at night.
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For example one of my female l. thayeri which is around 3 inches always retires for the night in the same corner. Anytime I'm looking for my n. marilynae in the 100 (48inchx24inch) i can almost find them in a ball near the front right corner:

And if you look at other pictures i've posted of this aquarium you will almost always find them in the same general area.

Still it isn't true of all fishes as the tucano and morse code have a greater tendency to roam as does the female sp winkelfleck. Also my domestic angelfishes are just as happy sleeping on the right side of the 12 foot tank as the left but the chocolates have their fixed spots as do most of the geo in the 8ftx4ft.

This makes things a bit convenient if i want to check on a specific fish i usually know where he is located - though it isn't uniformly true and like most cats in the world the cat fishes that aren't cave dwellers are found just about everywhere and can never be found when wanted.
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Talking about cave dweller - i have this domestic female bn who goes into a cave in the top of a piece of driftwood - straight down (if you ever been caving you know what i'm talking about); but her tail of course sticks up - but since her eyes are covered she forgets about the tail being visible for anyone who wants to locate her. It is enduring in a way but sometime when has to ask what is the point.

Anyway i did find it amusing that at midnight most of the fishes have found their little corners and fallen fast asleep (this seems less true in the smaller aquariums 'cept those that have specific territory like caves).

 

[GaryE]

This is good stuff. Keeping small fish in big tanks lets you watch a lot.
Since I'm just back from aquarium fishing in a country with very few species, I saw the same pattern. By about day 3, you could look at a habitat, and say which species you'd catch where, if they were there. Slow water, shallow and with bankside weeds? Chromaphyosemion biteniatum. The edge of flowing water, in eddies? Epiplatys togolensis and lampeyes. Very shaded, swampy moving water? Epiplatys grahami. River beaches? Lampeyes like normani. Lily pads on the edge of a moving stream? Look under for dwarf Cichlids.

We are very fortunate that if we have large enough tanks and small enough fish, we can reproduce 'sort of' natural conditions.

 

[WhistlingBadger]

Yes, that is interesting. When I had a southeast Asian 55g, I had a school of around 15 blue rasboras (Sundadanio axelrodi). I expected them to hide out in the greenery most of the time, as this was a community tank with some large pearl gouramis and some small but very active dwarf chain loaches. But what they actually did was stake out a spot about eight inches across in the open water area of the tank, and that's where they stayed, pretty much all the time. I never saw any aggression on their part, but the other fish left them completely alone and stayed out of their area. It was amusing to see this "shy, delicate species" being so assertive about their property rights.

 

[anewbie]

Yes, that is interesting. When I had a southeast Asian 55g, I had a school of around 15 blue rasboras (Sundadanio axelrodi). I expected them to hide out in the greenery most of the time, as this was a community tank with some large pearl gouramis and some small but very active dwarf chain loaches. But what they actually did was stake out a spot about eight inches across in the open water area of the tank, and that's where they stayed, pretty much all the time. I never saw any aggression on their part, but the other fish left them completely alone and stayed out of their area. It was amusing to see this "shy, delicate species" being so assertive about their property rights.

Tid bit there are two fishes now known as blue rasboras; Sundadanio axelorodi and Sundadanio goblinus.

 

[WhistlingBadger]

I believe S. goblinus is the more up-to-date name. S. axelrodi was split into several different species, if I remember correctly.

 

[anewbie]

I believe S. goblinus is the more up-to-date name. S. axelrodi was split into several different species, if I remember correctly.

Perhaps but there is also a s. axelrodi with slight differences in fin. If i trust the information i found s. axelrodi is very infrequenly imported and s. goblinus is much more common. There is a slight difference in the colouring and found in totally different locations.

 

[SammyTargo]

This is quite interesting. I noticed a similar thing with my old 135 gallon community Rio Negro blackwater natural/biotope tank. I attempted to make many caves and nooks for the cichlids I intruduced to the tank. I had put a pair of Agassiz Apistos, and a pair of checkerboard cichlids (Dicrossus filamentosus), along with many other fish but these are the important ones.

These fish are smaller, and found in such a large aquarium had the freedom to choose where they would dwell. To add, they were also the first fish I introduced to that aquarium. I had chosen myself where I think the dwarf cichlids would want to go as their territories, I thought of the bigger and more protected caves would be their choices. When they settled in, first the apistos, they chose a completely random spot that I thought was not concealed or useful whatsoever!

I thought to myself that it is not all bad, as the checkerboards are now free to choose these ridiculously good territories within the tank. When it came around time to introduce the checkerboards, they chose yet another crappy, unconcealed, unhabitable area to mark as their territory.

I started to track their behaviour and could never come up with a solution. I had done this many times in the past where I introduced dwarf cichlids into tanks, community or isolated. They always chose my carefully created shelters for their bases. It was remarkable how these ones chose the worst places in the tank, and when other fish were introduced that could increase their need for cover, like my Symphysodon discus school, and my group of 5 Geophagus winemilleri (often labeled G. sp. "Rio Negro").