Oranda missing a fin.

Question
Hi, I have had an Oranda (1.5in) and a Black Moor (2in) in a 50 litre tank for about 6 months, but for the last few days the Oranda has been lying on the bottom of the tank.  I've tried epsom salts, aquarium salts and lots of water changes, but today noticed that one of his fins is missing; it is slightly red but doesn't look too bad.  However, he hasn't been eating since and I've moved him into my old tank and filled it quite shallow so he can go for air easier. However, he doesn't seem able to swim at all, he moves around the bottom but can't get off the bottom, so I have been helping him to the surface every now and then.  

Also, as I only have one filter, the tank he is currently is has no filter, but when i tried to put him back in the main tank, the Black Moor was pushing him around a lot so I moved him back.

Will he be ok without a filter? And is it fair to keep him alive when he can't get off the bottom? And how often does he need to go up to the surface?

The tank is 72'F, and I usually change about a third of the water every week, and vacuum the gravel every fortnight.  However, I removed the gravel when the Oranda had been on the bottom for a day as I wasn't sure if it would be uncomfortable.

I would really appreciate any advice you could give.

Many thanks

Answer
Hi Nicola:  Which fin is missing.  He will be ok without a filter but you will need to change the water about every two days.  You can also see if he will lay on a plant or something like that near the surface.  Most fins grow back... so if you can hand feed him he will probably be just fine.  How long do you think his fin has been missing and what do you think caused the injury???? dave