Hi, new at this..harlequin rosabora


New Member
Oct 28, 2020
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Peabody, MA
i had 3 harli's, one died,, new tank with a betta. 10 gallon. plenty of plants and swimming space. so i waited a wk. then bought 2 more Harli's. so now i have 4. they are all separated. no schooling going on. one is staying alone in the flow of the filter. i believe he is male..long and slender body.. i also believe he is one of the new ones.. so i was reading that they know when they are not from the same group that was hanging out before the move... I will continue to keep my eye on him... i hope he is alright.. now that i am watching... i am now seeing him bully anyone coming into his space in the filter stream...hmmm? didnt notice that before..does this mean he is a dominant male? also, my betta has seemed to relax...yesterday he was chasing everyone. and rt now.. he is resting alot.. hard being a tough guy all the time i guess.. I try to make alittle nest for him at the top which i thing he likes.. he goes to get away from all of the hustle and bustle of the Harli's i guess... after all. he lived alone for 8 months, he is very hardy. but i think now after 3 to 4 wks of changes, new fish,fish dies, anonther new fish in.. and btw... he hated the beautiful gourami that i added 2 wks ago..i had to take the gourami back to the store...ok.. i know this was alot... alot going on.. oh..... and i didnt even tell you... that i think i had a gravid female... 5 days gravid, swimming normal.. eating normal and finally today, she is not bulging.. i think she may have reabsorbed the eggs( at least, thats what they say happens if she doesnt drop them.. thanks for reading...



Fish Herder
Apr 29, 2012
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Hokitika, New Zealand
Harlequins don't always school, so don't worry about that. But give the Betta more floating plants and things to protect him from the action


Fish Addict
Aug 27, 2017
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Actually the Harlequin Rasboras need to be in a group of at least 6.
They are one of the most tightest schooling fish that I have seen.
They moved together like an army.

But take note that I tend to see more Harlequin Rasboras that are skinny and infected with diseases.
So, beware when you buy them or any new fish.
Whenever you buy new fish, you may bring disease into your aquarium unless you quarantine them for at least 3-4 weeks.

Actually Betta is not suitable to be kept with most fish as it will chase or kill them.
I think you can only keep Betta with fish that are bigger than Betta.
But do ensure that the Betta doesn't have long fins and tail where other fish will nip them. Then it will be the end of your Betta.


Staff member
Global Moderator
Nov 28, 2006
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Teesside, UK
The tank in the photo looks like a tall thin tank. Can you give us the dimensions, please as it could be too narrow for fish like harlequins which need 24 inches/60 cm swimming room.

How new is the tank: did you cycle it before putting the fish in there, or perhaps use a filter from another tank? What are the ammonia and nitrite levels?
You mention the tank having plenty plants, but in the photo there appear to be a number of plastic plants - are there any live plants besides the piece of hornwort on the surface?