My Oscars

Question
I guess I should start by saying that I received 2 oscars for my birthday in
April.  They seem to be doing good and getting bigger.  I do have a few
questions though.  They started out in a 5 gal. tank because I was not ready
for them but a week later I went and bought a 30 gallon tank.   They seem to
like the tank and I don't think they need a bigger one yet.  I have gravel in the
bottom and a large decorative rock for them to kind of hide.  The first
problem I saw was that they would fight over the rock, so I bought another
one, which seemed to fix that problem.  The other problem I have been
having is that they are getting bored of their food.  I started off with regular
tropical fish flakes but they would not eat them after a few days.  Then I
started a pellet I bought at walmart.  They liked that for about a week and
decided they didn't want it.  I went to a pet store and then found a food that
the first three ingredents are whole fish.  They ate that for about a month,  
but again stopped eating.  So I tryed feeder fish, only the bigger one ate them
and he would not let the other one eat any of the fish.  About a week of that
and then they will not eat.  They did not eat yesterday or today yet, I am
going to get some feeders again to see if they will eat but they will not eat
any pellets anymore.  I know they eat a lot of different things... What else
should I try?  They are about 5inches each.  
I also have noticed something white growing on the heater...  Do you have
any idea what that would be??  I test my water weekly and it is always good
but I checked it today and the nitrates is in the danger level... how do I fix
that??  What gets rid of nitrates??  Is it the carbon filter??  I am new to fish so I
don't know what to do.  Any information for a new fish owner would be very
helpful...  Thank you so much for your time
Megan

Answer
Hi Megan,
What a neat Birthday gift! Two oscars!

Unfortunately the bad thing is, you weren't prepared for these soon-to-be trouble makers. (Only joking)

Oscars are great fish, but they have special demands that must be met for them to be happy and thriving. The two most important things to remember (you probably already know this) is they grow to 12 inches and produce a lot of waste. These two things mean that a very large aquarium is necessary for them to be in healthy water conditions long-term. Your 30gallon is OK, but you must and I absolutely mean -must- get them a larger tank as soon as possible. The presence of nitrates in the danger zone is a proven sign that two 5 inch oscars produce too much bioload (waste production) for that size tank. Bad water conditions such as this can cause Oscars to flucuate in their eating habits and they can eventually develop very hard to cure diseases like Hole-in-the-head which often cannot be reversed. So please up your water changing schedule. With two 5 inch oscars in a 30-gallon I would do at least twice or better yet three times a week water changes of 50% or more. Oscars thrive in large water changes. Many oscar owners drain the tank water to just about an inch above the oscar and then refill with fresh, dechlorinated and equal in temperature to the tank water.

Water changes should help your Oscars tremendously, but please try to get them in a larger tank as soon as possible. I would recommend a 55gallon since they can usually be bought as inexpensive kits at Wal-mart but a larger tank is always better. I currently have a mature Oscar alone in a 55gallon and he has already outgrown the width of the tank (from front to back) and he needs a larger tank already. I'm working on getting him into a 75gallon which has a wider front to back length.

The best solution to nitrates is none other than large water changes. Carbon removes other impurities from the water like discolorations or smells (it also therefore masks potential water quality problems which is kind of a bad thing)

The white stuff growing on the heater sounds like the type of fungus that grows where fish food gets lodged and settles. This would be very understandable since your oscars haven't been eating or if they have been eating, oscars always blow out little bits of their food as they chew and those bits can easily get lodged somewhere and start a fungus growth. It's not harmful to fish but you want to make sure no leftover food gets lodged from the oscars refusing to eat. Usually the white fungus doesn't reoccur once removed by scraping and siphoning it out with your aquarium vacuum.

Oscars do have mood swings and some days they decide to eat while other times they just flat out refuse. I would suspect water quality problems to probably be the biggest issue here. Oscars also may suddenly decide they dislike one food after eating it for many months. You have to work with them a lot. I feed my Oscar OMEGA ONE cichlid pellets which he loves. He likes them pre-soaked also so he doesn't have to do so much crunching and chewing. I really do not recommend feeder fish for your oscars. Feeder fish are never given proper care at petstores and so therefore they are almost always sickly and diseased. They can bring diseases in on your oscars and create a very bad situation. It's best to leave feeder fish completely out of the oscars diet. There are so many high-quality pellet and other fish foods available now that your oscars nutrition can be completely met without any feeders whatsoever.

Try increasing your water changes and see if that changes their appetite. Give them some time. Like I mentioned before, oscars are so moody sometimes that a slight disturbance around their aquarium may cause them to decide they don't want to eat. But most of the time, oscars are bold eaters and greet you with wagging tails and those big eyes anytime you approach their tank.

For more info on oscars, please visit-
http://www.oscarfishlover.com/
(This site also provides info on oscars that don't eat)

I really hope your oscars are able to be healthy and start eating well again. They could grow into big and beautiful fish that would be your "wet" pets for up to 10 years or more.. Hopefully all that is needed is just some extra water changes and maybe a bigger aquarium soon...

Best wishes,
Karen~