I need urgent help! If you have experience treating arowanas, please hear me out.

[GeometricNeck]

I have a 550-liter tank with one 20cm Asian arowana and two 10cm Atlantic tarpons. Two days ago, I did a water change using my usual triple-cartridge filter. But since then, my arowana has been breathing extremely fast and has lost its usual active behavior—it’s no longer swimming around the tank like it normally does.

The strange part is that I did the exact same water change in another tank, and the fish in that one are perfectly fine. Even the tarpons in the same tank as the arowana are acting completely normal.

I tested the water with a Tetra strip, and all the parameters seem fine. My biggest suspicion right now is chlorine because the filter I use to remove chlorine from tap water is about 1–1.5 years old, so it might not be working properly anymore. Once I realized this, I added a water conditioner to neutralize any possible chlorine, but so far, there’s been no improvement.

I don’t know what else to do, and I don’t want to lose my fish. If you have any ideas or suggestions, please let me know—I’d really appreciate any advice!

I’m not a native English speaker, so I used a translation for help. Sorry if there are any mistakes.

 

[skjl47]

because the filter I use to remove chlorine from tap water is about 1–1.5 years old, so it might not be working properly anymore

Hello; I do not know of the filter you used to remove chlorine. if it uses activated carbon (charcoal) it may be out of date. My suggestion is to change the water again using water conditioner.
I would be suspicious of the equipment used with the first water change. Hoses, buckets or some other piece of equipment may have been contaminated by some foreign material.

Good luck

 

[Chaitika]

How much water do you change and how frequently?

Are those tarpon wild caught?

Are there any other changes to the aro? Fins turning slightly reddish?

I'm sceptical of chlorine poisoning. Rapid breathing is one of the symptoms of chlorine poisoning but gasping at the surface is a more telling symptom. The fact that the tarpon were not affected at all by what could be a toxic dose of chlorine is also a consideration. There is no treatment for chlorine poisoning except for supportive care.

Unless another symptom appears or it improves on its own, I think all you can do is maintain good water quality.