Arowana in indoor pond on hunger strike 1 month+

Hello MFK,

It's been a while, but I need some help. Here are the facts:

I've got a 300 gallon rubbermaid stock tank pond (The 6' diameter one) in my basement laundry room with a shower curtain and clamps keeping it covered. The substrate is ~1" pool filter sand. The contents are one silver arowana ~18" give or take. Usually he eats hikari gold floating pellets from the surface, but he hasn't in a long time, I'm guessing going on a little over a month now.

Filtration is a FX5, 2 of the biggest hydro sponge filters and a power head sponge filter. Nitrates are about 10-30 PPM last couple times I have checked, I've done a 25% water change twice, and I've cleaned the FX5 by emptying it of the detritus filled water and shaking the sponges out in dirty pond water as not to remove too much beneficial bacteria.

I tried feeding him thawed market shrimp today, feeders the other day, and pellets on and off every couple days to get him to eat. Nothing has worked. There are no noticeable lesions or marks on the arowana, the gills look proper and he looks generally healthy.

Also, he used to be housed with some vieja, or paraneetroplus or whatever they're called now, in the pond (fenestratus, zonatum, regani etc.). Once the vieja reached sexual maturity though, the dominant female killed off quite a few of the other vieja, but never bothered the aro. That being said, I ended up getting rid of the last couple vieja since I couldn't keep the aggression down.

Is it possible that the arowana was stimulated to eat by the tank mates?

Is there anything else I can do to get him to eat? Get another larger more peaceful cichlid (like a snook or an oscar or something) to try and stimulate him to eat again?

Thanks in advance.

Thanks for the response!

I actually thought of the lighting issue, so I added a 5 arm directional floor lamp to the side that gives him "moonlight" at night, and then there is a double 8' fluorescent fixture right above the pond that we leave on during the day. I didn't notice any nitrites or ammonia in the test strip, but I got an API liquid test kit and will try testing specifically for those today.

I actually moved him around with the grabber arm I have for my planted tank (I had some shrimp in the claw and was dangling and dropping it in front of his face). He was so docile, just kind of letting me pull him all the way to the top of the water. I might net him out and see if I notice anything else, but I did get a good look at him when I brought him to the top of the water.

I agree about the difficulty of seeing in a pond. I didn't notice much of the cichlid aggression going on until it was too late, unfortunately.

Anyway, I'll get back with test results for ammonia.

Well it's May now, and he still hasn't eaten. I've tried live fish, frozen shrimp, frozen fish filets, earthworms, pellets, etc. This is a 6 month strike now. He swims around mid level and makes sudden jolts to the side of the pond if I reach my hands in to get the uneaten pellets out. I have no idea what else to try. No signs of gill curl, no drop eye, parameters are fine. I checked the temperature and it was about 80 degrees F today. I keep a shower curtain over the pond to reduce evaporation/heat loss.

Do fish suffer from some type of separation anxiety? Since he used to share this pond with the vieja's he ate when they did, and it was like a feeding frenzy whenever anything was thrown into the pond. Once they killed each other off, he just stopped eating altogether.

I have tried adding multiple different types of fish at this point, and I'm really at a loss of things to try. Most of the time I just added feeders and they had died rather quickly (I assumed due to the increased temp or stress or a combination of both).

Today I added 7 Buenos Aires tetra, a quick/somewhat aggressive warm water dither fish. They were all dead or near death within a few hours. The arowana did not eat any though. I noticed some redness by the heads and possibly some lesions or white puffy spots on the body. I'm not sure if it is the result of a fungus, bacterial infection or just stress from the giant arowana sharing the space with them.

I think this presence may be the root cause of the arowana's lack of appetite. But the arowana is showing no symptoms other than lack of appetite, (no redness, lesions, labored breathing, etc.). If anyone that could shed some light on this potential pathogen I would appreciate it!