Something Is Seriously Wrong!

[AmberLynn]

I set up my 29gal divided 2 nights ago. Its divided into 5 sections and houses 5 male bettas. Before you ask no I did not cycle the tank I just planned on doing large water changes to help with the levels and such, but I the tank was up and running for a long time before I put the bettas in it, it was a home to one lone convict who has since been rehomed. But anyway my stats are

Ammonia: 0.25
Nitrite: 0
Nitrate: 10
Ph: 7.8
Temp: 76F

Now all of the fish are not doing well, I have lost one, wintergreen passed away last night for no apparent reason. Now cinnamon is floating vertical and rainbow wont move from behind the heater. I took Fire out cause I dont want to lose him, damien and barney are just sitting at the top and won't move. I dont know whats wrong, None of them have any marks on them no stress lines, they're just dying Please help!!

 

[JustKia]

The "small" amount of ammonia you have going on there probably isn't doing them any good - that calls for a water change.
Also many males don't do well in divided tanks, they get stressed by it and you end up with sickly fish.

 

[AmberLynn]

They cant see eachother through the dividers so theres no reason it should stress them out, I've had many bettas in divided tanks before with no problems at all. Also im aware that the small amount of ammonia isnt good but ive done another water change, besides ive had small ammonia spikes in tanks before buts its never effected my bettas like this, so i honestly dont think its the ammonia

 

[WILDER]

Water changes and increase aeration.
How many filters are you running.
Not ideal to seperate tanks into five compartments as it causes desease due to the filter flow not flowing right, it's best to have a filter at each end of the tank.