# Behavior change in shelldwellers



## mmerose (Nov 16, 2019)

I have a 29 gallon tank with 6 N similis and 3 Aphanius mento (it was 2 pairs. One female died and I haven't been able to find another, despite searching online for months). About 1/3 is planted and there is a lot of hornwort and floating plants for the Mentos. The other 2/3 is sand and 60 - 70 shells and 2 small plants next to the glass.

The shelldwellers used to be very peaceful, just floating above the shells, cleaning out their shells and swimming slowly. They would chase the Mentos if they strayed into the shell area. About a week ago, the biggest 3 shelldwellers became aggressive. Until then, they did not go into the planted part and never went to the top of the tank but they now swim into the planted part and the upper part of the aquarium a lot and, if they see a Mento, chase it aggressively. The Mentos have a reputation for aggression but they act frightened.

Is this normal? I wondered if they are trying to expand their territory, but I didn't think they would want to expand it to the top of the tank. Is there anything that I can do to avoid bullying and fighting? I don't want to lose any more fish.

BTW, the Mentos are really cool. The males turned blue, practically overnight, and they fade if they are frightened, like from the gravel vacuum. They then turn blue again and are quite beautiful. The little female is friendly and takes food from my hand. I really don't want to have to give them up.

Thanks in advance for advice.


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## sir_keith (Oct 30, 2018)

mmerose said:


> ... I really don't want to have to give them up ...


It seems to me that if you want to keep the _Aphanius_- which are seriously cool fishes IMO- the simplest solution wold be to re-home some of the shell dwellers. It sounds like you have an excess of males anyway. Good luck. :fish:


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## mmerose (Nov 16, 2019)

Are the shelldweller who keep barging into the planted areas male? 
Is the tank overcrowded? I thought only 6 little shelldwellers would be okay. 
I've been looking for a female Aphanius for months. It seems like all of the internet fish places are sold out.


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## mmerose (Nov 16, 2019)

Is there any way to tell the sex of the shelldwellers? They all look the same except some are a darker color than others.


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## sir_keith (Oct 30, 2018)

mmerose said:


> Is there any way to tell the sex of the shelldwellers? They all look the same except some are a darker color than others.


Difficult when they are young, but eventually the males grow larger than the females.


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## mmerose (Nov 16, 2019)

Thanks, I think they are different ages - when I got them, a few were tiny, about 1/2" long. So I have to keep an eye on them.

Now there is another problem (I posted separately) - one of the big ones is bullying another one. They were so peaceful when they were young, it was very relaxing to watch them in their shells. Now they don't seem to dig in the sand or clean their shells much any more.


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