do fish sleep

Question
we recently were given a 75 gal tank with 15 fish not quite sure of there type they were very big and big  some  one was 10 inches 4 were 6 or 7 inches i think that they all were gold fish of some sort  we moved the tank and the fish
together and the water became very dark with stuff from the bottom of the tank .  long story short when we got it  to our house we basically started over emptied the tank cleaned every thing in and out of the tank . including the rocks i cleaned them they were the worst any how we have had the tank set up and running for about 3 weeks now and all the fish seem to be happy and moving allot eating all there food we added 4 new fish 3 days ago and removed  5 of the largest fish . two of the new fish we added are blood parrot fish  they are orange fish they seem to not be happy and not eat allot and lay at the bottom corners septet from each other  i don't know much of any thing about fish or tanks but I'm on a crash courser now.  our pH has been 7.0 or 7.2 from  day one and has not moved alot we were thinking that maybe the fish sleep at the bottom and rest  or that there is something wrong with the fish also  we bought the fish from wallmart don't know if that was a good idea now.  now that we have others told us to only buy from dealers.  not sure why . well i hope this is enough information for you to help us thanks  Sam and Carrie.  PS don't know the exact gal of our tank but it was really heavy to carry with the fish and water up two flights of stairs . the dimensions of the tank are 18 x 36 x 24 inches thank you hope to here from you soon

Answer
Hi Carrie:  fist thing you have to do is to identify what kind of fish you have.  If your original fish are in fact goldfish the blood parrot fish will most likely eat them... Blood parrot fish are cichlids.  The pH is good so long as it does not drop or rise too quickly most fish can live in pH of 6.5-8.0.  It may be possible that you have other cichlids at which point the parrots may be hiding because they are afraid of the other fish... very important.. find out what you have in that tank... dave