So, a friend of a friend (and no, I’m not talking about myself lol) has an Oscar that is approximately 10 years old…. housed in a 55 gallon tank by himself. Recently the fish jumped out of the tank breaking the hood! Luckily, someone in the house heard the noise and ran over to see what happened and put him back in. So he wasn’t out for too long. However, the fish may still be in shock and hasn’t been eating like he used to from what we’ve been told. Also, prior to this, the fish was being neglected by the owner whose daughter has now recently taken over caring for it. Her and her boyfriend are new to this but have been trying their best to take care of this guy. The water was in poor condition (leading us all to believe that’s why the fish tried to escape) and I am told that there has been a couple times in the past when a new piece of decoration was put in, that the fish would swim hard into it to knock it over. Don’t know if this was because of water conditions or if it just didn’t like that particular thing, but just trying to give a little background here. This guy looks to be pretty beat up, but has been through a lot over the years and is still going. A water sample was taken and tested at a local shop and definitely showed some problems (they didn’t mention to us what specifically was off, but said there was a lot of waste in the substrate and the water is definitely not clean looking, so I’m assuming the ammonia and nitrate levels are high at the very least). They were advised to avoid chemical treatments for now and to keep doing water changes and testing the water. Any other suggestions on what they can do to help this situation out more? They don’t know a whole lot about this but are trying their best to help this guy out. Also, the tank has been established for a few years now. It was in a smaller tank when the fish was smaller as well, but this person moved about 4 years ago and it was fostered at a pet store while he was moving and then he picked it back up eventually and put it into its current 55 gallon tank. As I said, that was around the beginning of 2021.
Where do I start??
First off, an Oscar that is 10 years old should be at least 12" long making a standard 55 gallon tank too small for him because he can't turn around without hitting the glass. The standard of a 75 gallon tank minimum for Oscars is for the 18" width which is what a standard 75 is. ( It's the same tank as a 55 only 6" wider. ) . So this fish, if it's less than 12" long, has most likely been underfed and/or stunted by the care it's received. This can also explain running into decorations because they take up valuable swimming space.
Oscars are one of the most intelligent fish we keep in tanks and as such, there is just as good a chance that the fish jumped due to seeing something that either startled it or thought he saw something to eat and tried to get it. They don't always realize that a lid is there, especially if it's a glass lid, that can stop them. They also get very attached to their caretakers so a new person may not be totally accepted at first. As for the fish not eating after the jump, how do you think you'd feel if you ran head first into a wall ( which was the equivalent of what happened when he hit the floor.
) Add to that poor water quality and you have a real situation that is not conducive for a happy fish.
As for the poor water parameters, to store is correct that this needs to be done with water changes and not chemicals. You need removal of the turds, not making them less toxic. They should be doing daily water changes of about 20%-25% while siphoning the poo out of the gravel. Not one large change or full gravel clean to avoid upsetting the biological filter. It's going to take a while to really get the tank clean but it didn't get dirty overnight so it can't get cleaned overnight either. Which leads to.......
...Filtration. Due to the fact that Oscars are so dirty, they need oversized filters to keep their environment clean. Big fish make big poo and big poo is heavier than small poo so not going to get picked up by slow filtration. All this adds up to why a 55 is too small for an adult Oscar.
Your assumption that the ammonia and nitrates are high is probably half right. A tank that small with a fish that big probably has a good biological filter bed so ammonia would not be the issue but a high nitrate level is more likely. This is another reason why doing more frequent water changes are necessary, no matter how large the tank, when keeping Oscars.
I would strongly suggest the people get a larger & wider tank for the fish to reduce all the maintenance they need to do and increase the fish's mental health. Without that, consider rehoming the fish, upgrading the filter and do more frequent weekly maintenance.
Since the fish has been on the floor, they will also need to watch for any bacterial or fungal infections from the floor. With the body slime missing where it hit the floor, it opens the fish to infections.
Hope this helps.
