Help needed quickly
 

Hello Arofanatic users!

I'm pretty new here, want to say that english isn't my first language, so the spelling might not be perfect!

I bought an Arowana (Silver) few months ago, it were pretty young & small when i got it, now its about 18-20 centimeters.

It's been feeding very well, started out with bloodworms and later on went over to mussels - which it really loves! Well loved, as recently (about 4-5 days ago) it started swimming around looking dizzy while it were gapping for air it looks like.

The tank is 500 liter, with 2 large bublers in giving plenty of air, pump is doing 2500 liter an hour & the surface is moving at all time. There's plenty of hidding spots for it to chill out, but yet it just swims around mostly with the mouth open slightly and doing the weird moves - it haven't been eating the past 5 days either which isn't normal as its really hungry all the time. There haven't been any changes BUT a pump change - I did use the old bacteries from the first pump, and I've done water tests quite a lot.

Everything were fine untill a week ago were the No3 amount spiked crazy, so I did some water changes (50% 2 times, then 30% 1 time) which got it down A LOT. It's currently on about 30-35 ppm, which is still to much, but I've read that the arowanas don't like all new water so i have to do it in a "slower" paste.

I've added water bacteries at every water change & added some salt + I've increased the temp to 30 (Did this over 3 days to prevent harming the fish).

There's 4 Bali sharks in the tank also, not very big ones so there should be plenty of space for them all.

I'm thinking that the new pump needs more time to get properly ran into the bacterial culture, so therefore i just have to do some waterchanges over time to get the No2 & No3 down?

Almonia level is fine, same with No2 - Ph have been very stable at 7-7.5.

Anything else that could cause this? Internal bacteries maybe? I do have cures for this but i rather not use the medicine if it can be prevented.

Read at another forum that lowering the water level with 30-50% for 2-3 days could be usefull, as the presure from the water will decrease, letting the fish breath and recover faster?

Anyway please let me know if anyone could know what might be the reason.

Cheers!
/sticky

i think you over-reacted on the dosing of bacteria and temperature. adding bacteria and increasing temperature at the same time is going to drive up the demand for dissolved oxygen.

You can consider reducing the water temperature to 28C (double check with another thermometer after you change the temperature on your heating rod, the thermostat in the heating rod might not be accurate) and stop dosing additional bacteria after every water change. given that ammonium and nitrite (NO2) are low, I think you have enough microorganisms within your system.

The best way to remove NO3 is water change. If you insist on the biological way, you'll need some oxygen deficient environment within your system for denitrification to take place (eg, sand bed, etc).

Salt is not required.

Anti chlorine is important during water change. The gills get injured and the fish will gasp for air when chlorine in the water is too much.

Yeah i might have overeacted a bit here, the doses of bacteria isn't much though - half of what is suggested. I'll lower the temp a bit and give it some days to see if it recovers.

Thanks for the reply :))

I'm using fine black rocks as buttom layer, have plants - which are growing pretty good i'd say.

May I have an idea of your filtration set up for the fish tank?
pictures of the overall tank, filtration layout will be helpful