Odessa Barb - New tank owner - Help

[Caffinated.cat]

Hi all I'm a new tank owner - I've had my tank now for about 2 months.
In the tank there are:

1 Odessa Barb
1 Leporinus fasciatus
1 Dwarf Rainbow
1 African Catfish
2 Clown Loaches
2 weird hybrid goldfish/dwarf rainbows - there were a few feeders that somehow survived and then these little silver fish with the same blue iridescent sheen the dwarf rainbow has suddenly showed up

Tank size: 55 gal

There's plants, driftwood, a rock cave, a taco decoration, a spongebob decoration, as well as an airator and a heater.

The water quality is

Ammonia: 0
Nitrite: 0
Nitrate: 80 - I know this is high and I'm getting a nitrate filter I remember seeing at the aquatic store I got my fish from.

The tank has a slight yellow hue.

About 3 days ago we removed the two remaining goldfish feeders still in the tank because they were harassing the African Catfish, causing him to start to become aggressive - he is an amazingly docile fish.

Since the two goldfish were removed, my Odessa Barb just lazily floats at the top of my tank. Prior to this she would routinely chase all of the goldfish around the tank until about a week or two ago when the goldfish reached her size. Still she would still stay towards the bottom with the other fish.

I know I need to get more Odessa's, but I'm worried that there may be something else wrong with her. Hopefully there will be at least another 4 Odessa's in the tank in a few days.

Any advice?

[Autumnsky]

Hello,
Your post was lost in the admin / announcement forum.

How is it going, sorry it took so long to find this?

Are you familiar with the nitrification cycle? If not too sure about it or want more helpful info for keeping fish check out the article link in my signature.

[pwypGlofish]

I know I’m not an expert at this, but when a fish stays in the top of the tank it means that there’s a lack of oxygen. Maybe your filter isn’t enough for a 55g? Just asking for how many gallons it opperates.

My advice would be to do frequent water changes (40% every week) until your nitrates levels drop because it makes your oxygen less likely to ventilate through your fish tank - Check water parameters often and tell us if it gets better

Hope your Odessa barb gets better! Don’t give up m8