Discus tank mates

Currently have a 300 litre (80 gallon) set up, with 7 discus (maybe 4.5 inches?) and around 25-30 cardinal tetras. Just wandering if I can add anything else to add a bit more movement? 50% water changes twice a week, heavily planted (more growth and additional plants than the picture), 2 x 1400l/h canister filters.

Rummy nose, rainbow fish, corys, other larger tetras or barbs all come to mind. Open to anything…

I don't know if you have room for more fish. When those discus get bigger they are going to take up a lot of space.

Rummynose tetras would be ok but they won't be colourful due to the white substrate and lack of surface plants.
Some rainbowfish might be ok but a lot of them carry Fish TB so I would avoid keeping them with discus unless you can guarantee they are free of TB.
A lot of barbs can be nippy or too boisterous for discus. Smaller ones like ruby barbs would be ok except they prefer much cooler water than the discus.
Some of the Corydoras might be ok but you would need to find fish that do ok at higher temperatures. Suckermouth catfish like Peckoltias, Farlowella and Loricaria sp would do better with the warmer water compared to Cories.

On a side note, some of the discus look like they have white edges to their tails. If this is correct, it's excess mucous and something might be off in the water.

Sounds like I’ll give new additions a miss… can you circle as to where the white edges are? That sounds concerning

X

Hopefully you can see the areas. I picked blue hoping it would contrast but it's hard to see.

I think that’s just the lighting. As you can see in the other picture they do not look like that

They look fine in new pic so that's good

The new pic makes it look like there is blue green algae on the sand. Is that another light illusion or do you need to clean the sand?

Oh yes, I was certainly battling various algae types and some pretty bad Cyanobacteria. It’s mainly under control now after manually removing it don’t have any newish pics of the tank at the moment, but will post a video tomorrow if you are interested

Beautiful. What plants are in the tank? Are you low tech, no C02? I've been thinking of adding plants in a few of the pleco tanks but not sure what can handle that heat without melting

No idea on the plants really, there’s defo some hygrophila and Valisneria but I simply bought all the stem plants from my local store and popped them along the back.Tank is sand at the front, and a mix of sand, gravel and whatever else I had from an old tank at the back. There’s a few root tabs popped along the back and I don’t run c02. Gets lot of natural light as well as the tank lights