3 replies to this topic

[Jrm2157]

I have two adult blackside darters. Are they known to be agressive towards one another. Ive had one for about a month now and recently caught another one to add to my 125 gallon tank. The first day I added the new blackside the original one followed it around and would vibrate on top of it every chance it could get. Almost appeared like a mating attempt. Now it seems as though the original just chases the new one around and pecks at it. He does not do that with any of the other fish and there are plenty of other darters and some sunfish in there. Any advice on what I should do? Im adding more rocks for hideouts and territory claims thinking that would help. Its tough I havent been able to find any info on how to tell a male and female apart from other than the obvious mating season colors which I dont think they are in. I attached photos of both of them. The lighter colored one is the original blackside in the tank

[littlen]

Your pictures are not attached, but by what you described, it was trying to mate!  The males 'vibrate' on the females to get them to release eggs.  Your original one is certainly a male, and likely the newcomer is female.  Male daters will spar with one another, but otherwise darters are very social and get along even during the mating season (which is now).

 

I had a small school of Blackside a while back but never saw any spawning.  I did witness some Bluebreast darters doing exactly what yours were, and I saw eggs when they were done.  My tank was a community 150g and was in a room with strong ambient light from outside.  My guess is the longer days triggered them. 

 

I would grab a few more and enjoy them interacting.

[Jrm2157]

Oops sorry heres the photos. Now however over the past few days the dont seem to be friendly anymore. The original darter will chase off the newcomer whenever they interact. Every once in awhile they can interact somewhat peacefully but the original
One seems to be aggressive now. Is it possible when I introduced the second one originally, that the first darter mistook it for a female? I would have thought they would have known right away.

Attached Files

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[littlen]

That looks like a male dressed up for the breeding season to me.  He possibly mistook the new addition to be female as you suggested.  If the new one is also male, it is considered competition and it will get run off.  It shouldn't be an issue so long as the new guy has places to hide and get away.  The original will settle down as soon as the breeding season ends.  Nice tank btw.