Algae?

Need to know what this is and what I can do to clean it up. I have one fish that is black not sure what kind of fish he is can’t remember and I have many others of goldfish I believe

Black/red algae is a sign of high phosphates. Either more regular water changes are required or your tap water has high levels of phosphate.

do vac the gravel?

this type of algea will grow all over dirty gravel.

does look a bit like red slime algea (cyanobacteria) which isnt an algea its a bacteria.

need to clean the gravel with next water change and do a large change. need to add more bacteria to the tank to help move it

can get this in bottles at the lfs

The 2 yellow fish in the tank are balloon mollies and they come in a range of colours including black.

The stuff on the substrate is blue green algae (Cynobacter bacteria) and lows nutrients, red light, low oxygen levels and low water movement.

You need to do a 75% water change and gravel clean the substrate every day for a couple of weeks. Make sure any new water is free of chlorine/ chloramine before it's added to the tank.

Take any ornaments out and hose them off to remove the bacteria.

Reduce feeding, especially dry foods.

If you have old fluorescent lights on the tank, replace the globes and fluoro starters. Get globes with a 6500K (K is for Kelvin) rating.

Increase aeration and water movement especially over the bottom.