Blood parrots get black spot disease. It is the ONLY fish that gets it.
Ok so they are smallish right? This is what you do... Go to Walmart/Homedepot/pick your poison and buy some teracotta pots and pretty coarse sand paper. (try buying 4ish, they are like 25c each) Get the ones that are as tall as your handish (like my measurments?)
Get some plants too if you don't already have plastic plants in the tank
Bring them home
Get a hammer
you are going to use the pots to make caves, so you need to use the hammer to create doors. Tap the pot at the top and make a little door, one that is big enough for the fish to swim and out of (the pots will be used upside down so the door gets broken in the rim of the pot) sand the rough edges. Put a few of these in the tank. Parrots are hiders sortof... they like their space, and they like ot have a spot to return to when they are scared. Each fish should be able to claim a spot.
Check your water, I'd bet your ammonia is really high, do a water change daily until it is back under control (could take a couple weeks)
Black spot is a sign of stress, probably due to water quality.
You said they were sitting in the corner so my guess is that they don't have a place that they like to hide yet.
Parrots like oscars interact with what is going on around them outside of the tank. It takes time for them ot acclimate to their new home.
So test water, make parrot fish houses.