oscar in a 20 gallon

[ewurm]

Change all the water you want to, just be consistent so you don't have pH swings. I change 50% weekly at least.

 

[Mystix212]

The only real damage you are doing is reducing the dam levels. I have diagnosed myself to be a small OCD sufferer but I always forget to do water changes.

 

[BichirAddict]

Hard to tell how long. Mine was at the same size you bought yours at and in about 6 months grew to 9".

 

[dzb912]

that happpened to my oscar afte r i move him because of a water chance
then he died

 

[mssassysan2000]

Yeah use salt raise the temp and every thing should be okdo a waterchange about a 20% waterchange do the trick.