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Just got a question about rainbow behavior. I have a 40 gallon with 2 Boesman and 2 New Guinea rainbows along with a couple of Blue Colombian tetras. Initially I had just the Boesman and the 2 fish would line up next to each other eyeball to eyeball and swim in a tight circle, sometimes on and off for a couple of hours in the morning. When I added the New Guineas, the largest New Guinea would take turns with the 2 Boesman doing the same thing. Is this just a territorial dispute between males? It never comes to anything but it's quite comical to watch. Also, is there a reliable way to sex rainbows? I think I have all males, but not quite sure??? thanks in advance for any responses....

It sounds like male displays, but if you want them sexed just post some pics

My boesmani males do this pretty much continuously -- it's pretty clearly territorial in their case. They never hurt each other -- just spend most of each day lining up eyeball to eyeball and posturing. This has been going on for a couple of years in my tank, and it took me awhile to figure out that it's nothing to worry about. It's just how male rainbows (at least the boesmanis) keep themselves entertained.

Nothing to worry about, it is displaying for breeding purposes. Rainbowfish don't fight per say but are more like peacocks. They are comparing size and color to determine who gets first crack at the top females and best breeding spots.

If they are doing the circle dance, they are almost certainly both males.

Sexing Rainbows is difficult in most species but here is what to look for.

1. Males are generally bigger and almost always more colorful than females.

2. Males have a more distinct lateral line. The lateral line in most species, Bosemani included, is a darker color.

3. I find this way to be inconsistent but anyway: Rainbowfish have two dorsal fins, a small one towards the head and a much longer one on the back of the body. The front fin on the males is longer and overlaps the back fin a little bit. The front dorsal on females is shorter and doesn't reach the back dorsal fin.

4. Males have a breeding stripe that flashes a different color from thier dorsal fins to their snouts. Some females may show a stripe but a strong flashing stripe would be a male. In Bosemanis the stripe is hard to see at times because it is a lighter color blue and not a different color. In Turquoise, for example, the stripe is yellow.

All of these methods work much better with mature fish, juvis are almost impossible.

this same thing has been happening to me over the last few days as well. mine will sometimes turn white and start fighting while doing this but i dont see any real damage.

Last edited by zachf92 at 02-Jan-2006 14:37

my boesemani keeps circling my powder blue dwarf gourami.

I wonder if this could be reason my pb gourami isn't doing well? Maybe intimidated and stressed?

That is strange behavior for a Bosemani. My rainbows don't even acknowledge other fish in the tank. How many Bosemani do you have? They are schooling fish and act wierdly if kept alone.

It probably is the reason why you're Gourami isn't doing well. They like things to be calm around them. The hyper-activity of rainbowfish can upset them. But if the rainbows are in a school and acting normally, the gouramis can usually find a peaceful spot and do fine.

yes, my boesmani and barred rainbows also did this to my dwarf gouramis as well.
I eventually had to remove the gouramis.


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