Are dwarf Oscars real?

[CatfishRampage]

You can bring a sample of water to an LFS and they can test it for you. Big box stores like PetSmart and Petco do it for free, so it should be the standard.
I believe you have a stunted fish. Does it have really big eyes or any other off-looking body portion? Likely not going to see it get much larger than its current size if it hasn't grown in the months you've been raising it.

Unfortunately my country doesn't have petsmart or petco

 

[Fishpony]

Unfortunately my country doesn't have petsmart or petco

I see, can you try to get your hands on some aquarium test strips? They'll give you a good approximation of your water parameters. Tetra EasyStrips are a good brand and hopefully, it isn't too hard to get your hands on them.

 

[phreeflow]

Post a pic, if it has a big belly and smaller than normal, maybe it’s a Shortbody oscar

But even then, it should be larger than 3-4”

 

[SilverArowanaBoi]

Yeah, short bodies aren't really "short" per se. Maybe you could put your fish into a new, larger tank? Maybe he doesn't like the conditions of the 55-gallon? Check water parameters. Are your other fish acting strange? That is another sign that your tank parameter/water quality isn't ideal. Also, if you feed him daily, maybe hold off for a few days (2-3) and see if he is just bloated from food. Check for any signs of disease. Is he acting alright? Is he swimming oddly?

It could be something simple like genetics; consider where you got him. Did you get him from a quality fish store with quality fish (quality fish store meaning healthy tanks suitable for the stock, healthy specimens who are active like they're supposed to be, very few to no dead fish in tanks, etc.)? Or did the store look suspicious with semi-healthy specimens (semi-healthy means fish were in semi-ideal conditions, and many fish were dead in various tanks even with healthy specimens, etc.)?

Also, you can get your water tested by any local fish store. Maybe you have a mom-and-pop fish store you could go to? Or you could even go to a "normal" pet store with fish for sale.

I hope this helps! Good luck!

 

[CatfishRampage]

I tried sending a picture but it doesn't work

 

[Deadeye]

In the typing box (I’m sure there’s a proper name for that), there is a small picture icon (between the link and smiley face). If you click that, you can add an attachment.
If on mobile, you can use the camera icon to directly take the pic and add it.