OSCARS & PLECOS

Question
FIRST OFF, I HAVE A 45 GALLON TANK WITH A TIGER OSCAR AND A AFRICAN CICHLID. I'VE HAD MY OSCAR FOR ALMOST 5 MONTHS NOW AND IT SEEMS HE HASN'T GROW AT ALL. HIS DIET CONSIST OF STAPLE PELLETS, FLAKES, AND HES ATE GOLDFISH BEFORE. I WAS WONDERING WHY HE ISN'T GROWING. ALSO SINCE I'VE HAD THIS TANK I'VE HAD 4 PLECOSTOMUS AND 2 OF THEM DIDN'T EVEN LAST A NIGHT. WHAT COULD BE MAKING THEM DIE OFF. MY pH IS 7.4 AND MY AMMONIA IS ALMOST NONE. I'VE USED STRESS ZYME, PARASTIE CLEAR, AND ACCU CLEAR IN MY TANK. MY FILTER IS FOR A 75 GALLON TANK
I HOPE YOU CAN HELP ME. THE PLECOSTOMUS IS MY BIG CONCERN!

Answer
Hi Jake,
Oscars need a 60 gallon tank all to themselves.  One Oscar needs this space to grow.  Two Oscars you must double this, and so on.  When an Oscar, or any other fish does not have the space he needs, his growth is stunted, his internal organs have no place to grow, and he dies a horrible death.  A healthy Oscar who has the space he needs will grow one inch a month.  Water changes every week of 25% must be made, always siphoning from the bottom.  The slightest ammonia in a tank is dangerous to fish.  Do small water changes everyday to get rid of it.  Check your nitrites, and nitrates also.  
Why your plecos die, is very difficult for me to know.  Do you buy them always at the same pet store?  Some pet stores don't feed their plecos, and when we buy them they are actually starving.  Sad but true.  We must feed our plecos like we do other fish.  He does not live on algae alone.  We must buy sinking wafer algae pellets, and sinking shrimp pellets.  They must be fed everyday.  The common pleco also needs a very big tank, as he grows very very big.  Plecos do not eat spoiled food at the bottom of the tank.  This may be what is happening, since your other fish aren't sick.  A starved pleco is very weak, and once their little tummies have shrunk, not many recover from starvation.  I can't think of anything else, since they have no sign of disease on their body.
Here is a list of foods that your Oscar should have:
Earthworms bought at the bait store, and cleaned.  (To clean the worms, put them in oats for one week or so, and always buy them at the bait store to avoid pesticides.)
Regular minnows bought at the bait store.
Crickets bought at the pet store.
Frozen fish that you buy at the market that come from rivers, and lakes.  They must frozen, and come from rivers, and lakes, and never salt water.  Chop pieces off, let it unfreeze, and feed this to your Oscar, he will love it.
Frozen Veggies that you blanched, and let cool.  Peas, green beans, broccoli, and carrots.  I buy mine frozen, and take out what I need.  Veggies are very good for Oscars, and they need it at least once a week.  I also feed mine spinach, and boston lettuce.  Wash the spinach, and lettuce well under cool water.
A good quality flake
Pellets, and Sticks
Frozen foods that you find at your pet store, such as bloodworms.

Never feed your Oscar feeder fish.  Feeder fish are almost always full of disease, and if eaten by your Oscar, he will also get sick.  Feeder fish have no nutritional value, therefore is not recommended for fish to eat.

I hope this helps.
Lynda