Oscar not growing

[Nickavfc]

I have a cichlid tank all fish are thriving apart from my oscar , hes eating and behaving fine but hes not growing hardly at all while my jack dempsey , acara , bala shark , jaguar are all thriving , surely its genetics ??

 

[Deadeye]

Welcome to the forum!
How big is the tank? That’s a lot of large fish that will produce a lot of waste and eat a lot of food. If the Oscar isn’t getting enough food, it will not grow. Additionally, a lot of fish produces a lot of nitrates, which show fish growth.
It is most likely not genetic - you will have a hard time finding oscars growing slowly given adequate conditions.

 

[duanes]

How much water are you changing per week?
What size tank?
What is your nitrate concentration?
Is your water hard or soft?
Sounds like you had a large number of cichlids already, before adding the oscar.
All cichlids produce growth inhibiting hormones, and the only way to get rid of them is by doing a lots of large water changes.
And it seems oscars are very sensitive to the above situations.

 

[Nickavfc]

Welcome to the forum!
How big is the tank? That’s a lot of large fish that will produce a lot of waste and eat a lot of food. If the Oscar isn’t getting enough food, it will not grow. Additionally, a lot of fish produces a lot of nitrates, which show fish growth.
It is most likely not genetic - you will have a hard time finding oscars growing slowly given adequate conditions.

But how come the other cichlids are growing and the oscar isnt ? If the what you say is right they all would be the same surely? I test water and do water changes every week

 

[Nickavfc]

But how come the other cichlids are growing and the oscar isnt ? If the what you say is right they all would be the same surely? I test water and do water changes every week

He eats well and its a 350 litre tank , theres more than enough room as they are fairly juvenile still

 

[FINWIN]

Sizes of all your fish? A juvie Oscar is 8 inches.
You didn't answer the previous question about your water change schedule. It's hard to help with incomplete information.

 

[Nickavfc]

Sizes of all your fish? A juvie Oscar is 8 inches.
You didn't answer the previous question about your water change schedule. It's hard to help with incomplete information.

I do a 25 per cent water change every week , oscar is about 3 inch whereas the others are 4 plus , the jack dempsey is running things in there dont know if this can affect oscar also

 

[Nickavfc]

Also goes s bit light in colours aswell , recently treated him for white spot also

 

[Nickavfc]

How much water are you changing per week?
What size tank?
What is your nitrate concentration?
Is your water hard or soft?
Sounds like you had a large number of cichlids already, before adding the oscar.
All cichlids produce growth inhibiting hormones, and the only way to get rid of them is by doing a lots of large water changes.
And it seems oscars are very sensitive to the above situations.

Would you say oscars are more sensitive than other cichlids ?

 

[esoxlucius]

My guess is the small Oscar is being bullied. It's recent white spot problem could have arisen due to it's immune system being compromised due to stress from the bullying. Losing colour and lack of appetite are also signs of stress.

Observe for now and try and catch the tank bully, probably the JD. May need to separate moving forward.