Emergency In Cycled Tank

[dipsydoodlenoodle]

I recently upgraded my female bettas from a 16 gallon to a 45 gallon tank; the 45 gallon tanks filters were in use for 18months before the girls moved in so they were fully cycled.

In the last 5 weeks (since the move) I added an L102 a few weeks ago, and 4 female bettas (a week ago).

The problem:
I've lost about 5 fish in the last 2 weeks.

One of the new ones died from dropsy , one of my girls was fine; when I got in from work she wasn't well and 40mins later she'd died. I lost another that had been loosing weight gradually for a long time (even in their smaller tank), I lost one from body rot (from the old tank - I couldn't cure her), and I lost 2 over night; one was perfectly fine until about 3 days ago when she lost her appetite; and the other was perfectly fine.

I tested the water on Thursday (before a water change) and ammonia was 0ppm, nitrites were 0ppm and nitrates were about 10-20ppm (it was hard to tell).

My boyfriend was wondering if the filter may be too strong for them? They don't seem to struggle with it .

All of the other fish seem to be nice and healthy, minus one of the new girls who has been inactive since I got her

Any idea what I can do? or what it might be?

Can I treat with myxazin (spelling?) with the L102 in there?

Thanks

Edit: After I tested the water on Thursday I was at a bit of a loss so I did a 90% water change.

 

[Blubble37]

hmmm, mystery disease. what i can say is that the filter wont be too strong and if it is there is always at least one place in the tank that is at a much lower water speed than the other places. As long as you are using the right size filter/powerhead for the tank, the outflow will be ok and will not harm the fish.

If you have a quarantine tank i suggest you put all the healthy ones in there until the wave of disease dies out in the main tank. Also keep treating the unhealthy ones in the main tank for whatever they have and remember that not all treatments can be used with other ones so read the label before treating with 2 different medicines. especiallt from different companys.

i find it kinda wierd that i ( a humble fish fanatic) am helping the top fo the food chain (leader ofd the fishes) LOL!!

 

[dipsydoodlenoodle]

hmmm, mystery disease. what i can say is that the filter wont be too strong and if it is there is always at least one place in the tank that is at a much lower water speed than the other places. As long as you are using the right size filter/powerhead for the tank, the outflow will be ok and will not harm the fish.

If you have a quarantine tank i suggest you put all the healthy ones in there until the wave of disease dies out in the main tank. Also keep treating the unhealthy ones in the main tank for whatever they have and remember that not all treatments can be used with other ones so read the label before treating with 2 different medicines. especiallt from different companys.

i find it kinda wierd that i ( a humble fish fanatic) am helping the top fo the food chain (leader ofd the fishes) LOL!!

There is no outward signs of illness that is my problem. I can't tell which are healthy and not (except the 3 that were ill before).

I'm absolutely stumped as to what it could be

 

[Blubble37]

that is a problem, oh dear.