Mango and Sir Charles have been tank mates from day one. In the last week they have suddenly started fighting. I know that this is not unusual. But Sir Charles is almost DEAD! I put him in a hospital tank, he is holding on but just barely. I have put metafix in the tank and a little sea salt. I there anything else that I can do! He looks so pitiful laying on the bottom of the tank, still breathing.

in order for us to help you, please give us info on:
1) How big are your oscars?
2) How big is your tank?
3) capacity and type of filter pump?
4) Any tankmate/s?
5) water reading as to ammonia? nitrite? nitrate? pH?, temp?
6) foods?

i am surprised that bullying reached to that stage immediately.
perhaps, stress had added in someway why it is acting as dead.
aside from bullying, perhaps, there are some contributing factor
on the aggression issue.

btw, welcome to the site in this uncomfortable situation for you.

My guys are only babies now about 6" long I have them in a 20 gal tank right at the moment I am putting my 40gal up very soon. I knew they would be getting big. My husband unfortunatly does not know how big they get because he got them for me as a present. I have had dealings with Oscars in past times. I know how they can be. But I have only had one at a time. Not two. The water at this moment seems to be off, nitrate is 0, nitrite is at 0 I live in a place that has hard water, so I use purified water but the hardness scale is at 300? Total alkalinity is 300 ph is is at 7.8. I was out of town for a week my husband was in charge of our little devils. All he knows is to feed them.
I am now feeding them flakes, but I give them rosies when I can. I also have a dragon fish in the tank, he stays in his log but feeding him is kinda hard. And 2 plecos. That is it. I don't like using the flake food is makes the tank messy. I have had these guys for almose a year. maybe. They have always been together. Nothing has changed in the tank. When I got home I observed their behavior. They were locking lips and fighting. I would have thought that Sir Charles would have been a bully but as it turn out Mango is the aggesive one. I put Charles in a hospital tank that I have set up for these occasions and to hold bait for them. I will work on the water situation. Charles is laying on his side but still hanging in there. He is a tough guy. I just hope that he will still be alive in the morning. He is not taking food but is perking up just a bit. It is amazing how attached you get to these guys. They have a lot of moxy in them. I Love them to death.

I hope that this info will help you to help me save my Charles. He is a beauty.

thanks for the input. now, we can analyzed the problem.
first of all, your tank is way too small for your stock.
small space can be attributed to the bullying.

2nd, your plan to upgrade to 40 gal is not enough with
your fishes. one full grown oscar needs at least 55 gal
tank. having additional tank mates envite more trouble.
no matter what filtering machine you put into, you will
still have water issue in your present set-up.

with hard water, 1 table spoon pure salt is needed for every
25 gal water to soften it and to enhance oxygenation.
lip locking is just one character of oscar as they matured.
territorial issue is another. if you have good tank size,
your oscars should be 10 inches long or more by now. having
said all, i suggest you aim for a bigger tank to keep them all
happily..say 125 gal size or more with good filtration too.

is Charles tank have cycled water? i suggest you add same pure
salt in the hospital tank, raise temp to 80 deg to comfort him/her
feed sparingly to minimized bio-loads. upgrading is a must a.s.a.p
or re-home some of them. sorry for unfavorable comments but that
is how responsible fish keeping is.

nevertheless, the decision is still in your hand.
good luck.

Polgara wrote:


a 40 gallon tank as paul has said is not near large enough for 2 oscars. when you add a goby and 2 plecs(assuming they are sailfin plecos) into the mix you should be aiming for a tank in 180 gallon range with the appropriate filtration to go with it. the oscars can and should grow to about 14 inches in length when mature and the plecos to around the 18 inch mark.




it is impossible to have an established tank and have a nitrate reading of 0. especially with you fish load and small tank. also you have no reading for ammonia for you water readings. ammonia is the most important one of all to check on since it is the most toxic compound to your fish.
i would suggest you retest your water and repost your readings again.



rosies and all feeder fish have little to no nutritional value and imo should not be fed to your oscars. a quality pellet should be used as a feeding staple with a mixture of other foods for treats such as shrimp krill earthworms crickets mealworms ect..





after a year your oscars should be around the 8-10 inch mark not 6. this is probably due to the tiny tank they have been kept in. imho they have been stunted and this should be rectified as soon as possible to avoid future health problems. contrary to popular beleif fish do not grow to their enviroment. even though they might can be stunted in their overall lenght their internal organs will continue to grow and cause health issues in the future. to remedy this problem they have to be rehomed into a larger tank asap.

as for charles in the hospital tank all i can recomend is to keep the water in pristine condition and if he has abrasion add melafix to the tank and hope for the best. oscars are very resiliant fish and have amazing powers of recouperation.

good luck to you with your fish and welcome to the site

Thanks everyone for your input. As I said in my last post, these guys were a gift, that being said, I realize that my tanks are too small. It is a very expensive hobby. This I know from the past. I have been working very hard to get them into a bigger tank. I am not use to the water where I have just recently move to. I can't even get my skin and hair to do right with the water. It is also undrinkable. That is why I use purified water. Now I know more on what I should do for my guys, I have always tried to be a responsiable animal keeper. I just wish people would stop giving me animals that I don't have the proper equipment for. Thanks Everyone again for your input.

most of us start knowing nothing. the important things is, we are willing to learn. this site will always help every one to be a happy fish keepers. that one is for sure.

I recently had a problem with my 2 oscars fighting. They were about 9inches long and had always got on fine and would never leave each others side till one day i came home and they had been fighting big time and one was clearly alot worse off then the other one. I had several attempts of sperate them and re-introduce them but the fighting continued. After some research and posting on this great site i determind the problem as they were both males who just reached maturity and were fighting to be the boss of the tank. I was left with no option but to rehome one of my O's....was sad but it had to happen. Hope the O that was beaten up pulls through, but as the other guys said you need a bigger tank.

I am sorry to report that Charles died last night. It was very hard for me, I know it is just a fish, but you get attached to them. Charles was my fav. Now I guess Mango will have the rule of the roost.

sorry for the loss. keep an eye with Mango.
he/she should be fine.

very sorry to hear about your loss...........

Thank you everyone for your help and loving condolences. I think I have found a new home!