You need a filter. Without it, there's no biological filtration and ammonia/nitrite will build up in the tank and poison your fish.
I have a female con..with no tail at all..down to as far down as your is..now i think mine happened at a very young age..and she is almost full grown now..so i dunno its your call your fish.
If he looks like he is suffering to much i would put him down..
But if it was me..and the fish looks like it is TRYING to survive and is fighting to make it..than i would give him a shot but if he is twitching and going up side down than i would put him down.
...I have pics of my girl if you want but i dont want to derail.
Look, we as humans are not fish, we can not tell what they truly feel and we probably never can. No one can say for certain that this fish is suffering or if truly wants to live on, nor can we say that any fish we have is happy where it is in the tank or is suffering from stress and wants to be released. Signs can be seen and all that, but what truly goes on in their heads, we will never know.
To look at a fish missing a tail or a fin or is blind in one eye or whatever and say that it is suffering is just us projecting our own emotions into the fish - the fish could be fine and in fact give no two ****s, just being happy to be alive.
Look, we as humans are not fish, we can not tell what they truly feel and we probably never can. No one can say for certain that this fish is suffering or if truly wants to live on, nor can we say that any fish we have is happy where it is in the tank or is suffering from stress and wants to be released. Signs can be seen and all that, but what truly goes on in their heads, we will never know.
To look at a fish missing a tail or a fin or is blind in one eye or whatever and say that it is suffering is just us projecting our own emotions into the fish - the fish could be fine and in fact give no two ****s, just being happy to be alive.