Spinning oscar fish

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AlexT88

Aquarium Advice Newbie
Joined
Apr 3, 2025
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Right now, I don’t know what’s wrong with my fish. Sometimes it stays in the upper corner with a very dark mouth and overall dark coloration, swims in circles, and stays upright with its head upright,
Sometimes it also seems to be breathing heavily.


Other times, it seems completely normal for periods.





I’ve done a large water change, raised the temperature to 25-26°C, reduced the lighting, turned off the internal pump, and I’m waiting for Seachem Stress Guard. It has done this before for short periods and then returned to normal, but this time it has lasted for four days. It didn’t eat for three days, but it ate a little yesterday.





It’s an Oscar cichlid that I’ve had for five years, so I’m really frustrated. What should I do?
1~What type of fish is afflicted? In addition, please describe what is wrong with the fish to the best of your ability (i.e. cotton like growth, bloated, etc.) ( answer )

2~What are your tank parameters (ammonia, nitrites, nitrates, temp, pH)? Please give exact values. ( dont know, put i add seachem prime in )

3~ How large is the tank? How long has the tank been set up? 530 liter, many years

4~What type of filtration are you using? Please give the name and number (i.e. Fluval 304) and amount of gph if known. ( eheim pro 2 )

5~How many fish are in the tank? What kinds of fish are they and what are their current sizes? ( A pleco and one algae eater fish )

6~When is the last time you did a water change and vacuum the gravel? ( 3 days and 2 days ) How often do you do this? ( not enough i think now ) How much water do you remove at a time? 25 %

7~How long have you had the fish? 5 years. If the fish is new, how did you acclimate it/them? Dont know?

8~Have you added anything new to the tank--decor, new dechlorinator, new substrate, etc.? No

9~What kind of food have you been feeding your fish, have you changed their diet recently? Pellets and no
 
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Unfortunately, without knowing your water's parameters, it's hard to say exactly what the problem is. If the fish ate a little after doing the water changes, that points towards the problem being water quality. Oscars are very dirty fish and should have their water being changed weekly if not twice weekly. A 25% change weekly is not that unusual for the typical aquarium but Oscars and Plecos are not the typical fish. A change that small should be done twice weekly for those fish.
That doesn't rule out other possibilities but without visually seeing the fish, it's hard to point to any disease. Please post either pictures or a 1 minute video of this behavior. (y)
 
Unfortunately, without knowing your water's parameters, it's hard to say exactly what the problem is. If the fish ate a little after doing the water changes, that points towards the problem being water quality. Oscars are very dirty fish and should have their water being changed weekly if not twice weekly. A 25% change weekly is not that unusual for the typical aquarium but Oscars and Plecos are not the typical fish. A change that small should be done twice weekly for those fish.
That doesn't rule out other possibilities but without visually seeing the fish, it's hard to point to any disease. Please post either pictures or a 1 minute video of this behavior. (y)
Thank you so much for your answer, and you are absolutely right about everything you said! The first thing I will do tomorrow is get it checked at my fish store. But a long time ago, I did that when I mentioned it had done the same thing for a short time, but everything was perfect back then.





I just added Prime Seachem yesterday – a double dose – and treated it today. I also changed 40 percent of the water 3-4 days ago and 25 percent the day after before adding it. But yes, I probably haven’t changed enough. However, I have never experienced issues in the same way as now.





I will record a video tonight, and thank you so much for your answer!
 
Thank you so much for your answer, and you are absolutely right about everything you said! The first thing I will do tomorrow is get it checked at my fish store. But a long time ago, I did that when I mentioned it had done the same thing for a short time, but everything was perfect back then.





I just added Prime Seachem yesterday – a double dose – and treated it today. I also changed 40 percent of the water 3-4 days ago and 25 percent the day after before adding it. But yes, I probably haven’t changed enough. However, I have never experienced issues in the same way as now.





I will record a video tonight, and thank you so much for your answer!
Just remember, you can not upload a video directly to this site so you want to upload it to a site like Imgur or Youtube or the like then copy and paste the URL or link to here so we can find it. I'll check back later. (y)

Make sure you get test results for pH, Ammonia, Nitrite, Nitrate and General Hardness. You want the numbers, not an "Okay" or "They are fine" answers. (y)
 
Just remember, you can not upload a video directly to this site so you want to upload it to a site like Imgur or Youtube or the like then copy and paste the URL or link to here so we can find it. I'll check back later. (y)

Make sure you get test results for pH, Ammonia, Nitrite, Nitrate and General Hardness. You want the numbers, not an "Okay" or "They are fine" answers. (y)
Okay, I’ll try and see if I can figure it out. But since I did a 40% water change about 3-4 days ago and then 25% the day after, I was considering doing another one yesterday. How often should the water be changed when the fish is sick?
 
Just remember, you can not upload a video directly to this site so you want to upload it to a site like Imgur or Youtube or the like then copy and paste the URL or link to here so we can find it. I'll check back later. (y)

Make sure you get test results for pH, Ammonia, Nitrite, Nitrate and General Hardness. You want the numbers, not an "Okay" or "They are fine" answers. (y)
. I’ll try sharing the link—let me know if you can’t find it.
 
. I’ll try sharing the link—let me know if you can’t find it.
That doesn't look like disease. It looks like he's just trying to reposition himself in small quarters. Are those rocks overhead or it just looks that way from the camera angle?
 
Undskyld alle mine
That doesn't look like disease. It looks like he's just trying to reposition himself in small quarters. Are those rocks overhead or it just looks that way from the camera angle?
It looks like it was just the background or the camera angle, but his behavior still seemed strange. He was in a corner, and every time he tried to swim, he spun around uncontrollably. He stayed in that corner the whole time and had a black area under his mouth. He also didn’t eat for three days, which is very unusual because he normally begs for food every day.





After a water change and treatment with Seachem Prime yesterday, followed by Seachem Stress Guard today, he has started to look more like himself this evening. I plan to do another water change tomorrow and continue using Stress Guard every 24 hours. As you suggested, I will also check the water parameters. I always do a 25% water change every Sunday as part of my routine, so hopefully, with these adjustments, he will fully recover.
 
Undskyld alle mine

It looks like it was just the background or the camera angle, but his behavior still seemed strange. He was in a corner, and every time he tried to swim, he spun around uncontrollably. He stayed in that corner the whole time and had a black area under his mouth. He also didn’t eat for three days, which is very unusual because he normally begs for food every day.
Okay, it looked like he was hiding under a rock ledge. Hiding is not really unusual for Oscars because they are frequently seen lying down on their sides. He should have a nice size cave or covered area to call home. By nature, Oscars are not really active swimmers. They like to find a place to call home and spend their time redecorating it.
After a water change and treatment with Seachem Prime yesterday, followed by Seachem Stress Guard today, he has started to look more like himself this evening.
That's a real sign his water quality is bad. You may not see high numbers now that you have done all the water changes but now you see how it takes all those water changes to get him to be " normal". The issue is probably high nitrates which happens when you don't change water often enough.
I plan to do another water change tomorrow and continue using Stress Guard every 24 hours. As you suggested, I will also check the water parameters. I always do a 25% water change every Sunday as part of my routine, so hopefully, with these adjustments, he will fully recover.
I would add another water change on Wednesdays as well as Sundays. When it comes to Oscars and larger Plecos, they can never have too much clean water. (y)
 
Okay, it looked like he was hiding under a rock ledge. Hiding is not really unusual for Oscars because they are frequently seen lying down on their sides. He should have a nice size cave or covered area to call home. By nature, Oscars are not really active swimmers. They like to find a place to call home and spend their time redecorating it.

That's a real sign his water quality is bad. You may not see high numbers now that you have done all the water changes but now you see how it takes all those water changes to get him to be " normal". The issue is probably high nitrates which happens when you don't change water often enough.

I would add another water change on Wednesdays as well as Sundays. When it comes to Oscars and larger Plecos, they can never have too much clean water. (y)
Yes, that’s right—he also has a spot where he “relaxes” on the other side of the tank, where there’s a big branch sticking up. I just didn’t film that part. It’s a 530-liter tank, so it’s fairly large. I used to have plants in it, but the other fish keep eating them—and they’re pretty expensive!


You’re definitely right, and it’s not good—I’ve taken that to heart now!


Awesome, I’ll do that. I really appreciate you taking the time to reply and give advice.





The people at my fish store told me it was swim bladder disease, but I recently had a Flowerhorn cichlid with that, and I had to put it down, so I know it wasn’t the same thing. It’s really nice to have someone to talk to about this since I don’t know many people with experience keeping fish.
 
Yes, that’s right—he also has a spot where he “relaxes” on the other side of the tank, where there’s a big branch sticking up. I just didn’t film that part. It’s a 530-liter tank, so it’s fairly large. I used to have plants in it, but the other fish keep eating them—and they’re pretty expensive!


You’re definitely right, and it’s not good—I’ve taken that to heart now!


Awesome, I’ll do that. I really appreciate you taking the time to reply and give advice.





The people at my fish store told me it was swim bladder disease, but I recently had a Flowerhorn cichlid with that, and I had to put it down, so I know it wasn’t the same thing. It’s really nice to have someone to talk to about this since I don’t know many people with experience keeping fish.
Oscars used to be my forte. ;) I had 13 breeding pairs of them at one point so I've seen a lot of behaviors with this specie. They are one of the most intelligent fish we keep in the hobby so they know how to manipulate their owners. LOL I had one that would suck on my thumb when I would be cleaning his tank. I had another that would cuddle inside my cupped hand if I put it in the tank. Back in the 60s, there was a book that reported that a fellow in Germany taught his Oscar to pull a string that rang a bell when he wanted to be fed. So you can see, they are no dummies when it comes to intelligence. Their only downside in my opinion, is that they need a lot of water changing. It takes clean water and a good diet to keep them healthy and away from diseases like Hole in the Head or Lateral line disease. I'd consider adding some frozen foods to his diet so that he eats more than just pellets. Oscars will eat a large variety of foods so the sky is almost the limit. Shrimps, Fish, Earth Worms, Insects and Lizards all have been eaten by my Oscars. (y)
 
Oscars used to be my forte. ;) I had 13 breeding pairs of them at one point so I've seen a lot of behaviors with this specie. They are one of the most intelligent fish we keep in the hobby so they know how to manipulate their owners. LOL I had one that would suck on my thumb when I would be cleaning his tank. I had another that would cuddle inside my cupped hand if I put it in the tank. Back in the 60s, there was a book that reported that a fellow in Germany taught his Oscar to pull a string that rang a bell when he wanted to be fed. So you can see, they are no dummies when it comes to intelligence. Their only downside in my opinion, is that they need a lot of water changing. It takes clean water and a good diet to keep them healthy and away from diseases like Hole in the Head or Lateral line disease. I'd consider adding some frozen foods to his diet so that he eats more than just pellets. Oscars will eat a large variety of foods so the sky is almost the limit. Shrimps, Fish, Earth Worms, Insects and Lizards all have been eaten by my Oscars. (y)
Wow, that’s honestly impressive! So you really do know about them. And yeah, I can definitely tell you—he knows how to manipulate me and drive me insane. He follows me every time I walk by, all day long, if he doesn’t get food for just one day! 😂





They’re super smart though, and they do the funniest things. Today he was doing that tail-vibrating thing havent seen that before? 😅 Haha!
Mine even jumps up and either bites my hand or splashes water




Okay, I’ll try buying some frozen shrimp so he can have something different than just pellets. 🔥 He seems to be doing well, but he was spinning around again when the lights were off—and as soon as the lights came on, it was like a whole different story.
 
Wow, that’s honestly impressive! So you really do know about them. And yeah, I can definitely tell you—he knows how to manipulate me and drive me insane. He follows me every time I walk by, all day long, if he doesn’t get food for just one day! 😂
Yup, they know how to get what they want.
They’re super smart though, and they do the funniest things. Today he was doing that tail-vibrating thing havent seen that before? 😅 Haha!
Tail vibrating can mean a few things. Unfortunately, one is good, one is bad. Tail vibrating is a way Oscars show dominance to other fish or as a way of enticing a mate. They will also do this when water quality is poor so it's a sign to clean the tank and water better. In your case, both things could be possible since you have other fish in with the Oscar and you have been lax in doing water changes. As the water quality improves, you'll be able to rule out water issues. (y)
Mine even jumps up and either bites my hand or splashes water




Okay, I’ll try buying some frozen shrimp so he can have something different than just pellets. 🔥 He seems to be doing well, but he was spinning around again when the lights were off—and as soon as the lights came on, it was like a whole different story.
From what I saw in the video, it looked like the fish was looking at something at the surface then got scared off while going after it. Originally I thought it was the rock overhang that he was getting too close to but you say that is not possible so he may have seen something else and changed his mind. Oscars will often eat bugs or lizards from the surface so them looking up is not all that uncommon. As for adding the shrimp, that's good but the more variety of foods you feed, the better the fish will be. It also protects their feeding should one food not be available for whatever reason. With mine, I had to learn how to breed goldfish and livebearers so they had live fish available to eat along with everything else. I never wanted them to get used to just one food. (y)
 
Yup, they know how to get what they want.

Tail vibrating can mean a few things. Unfortunately, one is good, one is bad. Tail vibrating is a way Oscars show dominance to other fish or as a way of enticing a mate. They will also do this when water quality is poor so it's a sign to clean the tank and water better. In your case, both things could be possible since you have other fish in with the Oscar and you have been lax in doing water changes. As the water quality improves, you'll be able to rule out water issues. (y)

From what I saw in the video, it looked like the fish was looking at something at the surface then got scared off while going after it. Originally I thought it was the rock overhang that he was getting too close to but you say that is not possible so he may have seen something else and changed his mind. Oscars will often eat bugs or lizards from the surface so them looking up is not all that uncommon. As for adding the shrimp, that's good but the more variety of foods you feed, the better the fish will be. It also protects their feeding should one food not be available for whatever reason. With mine, I had to learn how to breed goldfish and livebearers so they had live fish available to eat along with everything else. I never wanted them to get used to just one food.

Shrimp is the most accessible option near me, but I’ll absolutely take your advice and look into other pellets, insects, and the things you mentioned to help vary his diet. I actually remember a crane fly once flew into the tank, and Oscar immediately shot up to the surface and ate it — so I’m pretty sure he’d enjoy those!

It might’ve been what you mentioned, and honestly, I’m just really relieved it wasn’t some kind of disease. I already lost a Flowerhorn cichlid I was really attached to — it had so much personality. I’ve never been a fish expert, and throughout this journey I’ve made a lot of mistakes, lost some fish, and even ended up giving quite a few away. I did a ton of research before getting started, but things don’t always go the way you plan.
 
Shrimp is the most accessible option near me, but I’ll absolutely take your advice and look into other pellets, insects, and the things you mentioned to help vary his diet. I actually remember a crane fly once flew into the tank, and Oscar immediately shot up to the surface and ate it — so I’m pretty sure he’d enjoy those!

It might’ve been what you mentioned, and honestly, I’m just really relieved it wasn’t some kind of disease. I already lost a Flowerhorn cichlid I was really attached to — it had so much personality. I’ve never been a fish expert, and throughout this journey I’ve made a lot of mistakes, lost some fish, and even ended up giving quite a few away. I did a ton of research before getting started, but things don’t always go the way you plan.
"but things don’t always go the way you plan." Boy is that true. LOL Then you have those fish that haven't read their bios and act totally against what they are reported to do. :ROFLMAO: :ROFLMAO:
 
"but things don’t always go the way you plan." Boy is that true. LOL Then you have those fish that haven't read their bios and act totally against what they are reported to do. :ROFLMAO: :ROFLMAO:
Hahaha, no, it’s definitely not supposed to be easy! 🤣


But here’s a little update on my Oscar: after many water changes, some Seachem Prime, and lots of StressGuard, it gradually started to get better… and now, I haven’t seen it spin around for a few days! 🙏🏽


I’ll see if I can make a YouTube video about it one of these days.
 
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