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 if it uses activated carbon (charcoal) it may be out of date.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.

 

[GeometricNeck]

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.

Thanks for the reply! I usually change the water once a month. Honestly, I don’t know much about the tarpons. I spoke with a few experienced people around me, and they also said that chlorine poisoning is the only likely cause in this situation. They advised me to add activated carbon to my filter and support the process with a high-quality water conditioner.

As you said, I’ll try to improve the conditions and wait to see if there’s any change.

 

[GeometricNeck]

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

Thanks for the reply! Yes, I’ve been using my filter for a long time, and the carbon has probably expired. My previous fish might have been able to tolerate chlorine, so I never took any precautions regarding the carbon’s lifespan.

Right now, everyone seems to agree that this is chlorine poisoning. I’ve already started making adjustments—I added activated carbon to my filter and will support the process with a high-quality water conditioner. Hopefully, I’ll get through this without any issues.

I also have a dedicated hose for water changes, and I don’t use it for anything else, so I don’t think that’s the cause.

 

[skjl47]

change the water once a month

using my filter for a long time, and the carbon has probably expired

seems to agree that this is chlorine poisoning.

added activated carbon to my filter

Hello; First the water change (WC) schedule. I do not recall if you have mentioned the size of your tank. But you have fish which get large. So umless the tank is something along the size of a swimming pool, once a month is not enough. If the tank is in a mere few hundred gallons then with those fish perhaps a WC at least once to maybe twice a week.
Next the carbon. Activated carbon (charcoal) does not last very long at all. Days to weeks in some cases. Again I am not familiar with the stuff you use. I stopped using activated carbon years ago.
Next - I do not have an opinion on the chlorine poisoning. That the second tank was not affected raises a question. Best explanation i can think of is that your water company is like my company. They sometimes put in extra chlorine after a water line repair or other such event. That leaves a slug of strong chlorine in the lines for a short time. Perhaps you flushed the extra out during the first tank WC. Just a guess on my part.

 

[stratos]

I recommend using Seachem Prime when doing water changes. It is very economical.

 

[Americancichlidsaredabest]

I recommend using Seachem Prime when doing water changes. It is very economical.

If you have I’d say over 100 Seachem safe is even better