Goldfish feeding an deformity

Question
Hi, I have 2 young goldfishes. I been doing some research and I started feeding them peas. I fast them on the day b4 i feed them the peas because i'm scared I'll make them bloated.

I was looking online and they said you can feed them lettuce, preferably Romaine lettuce. Jus wash it in warm water an clip it to the tank. I was wondering. Do i jus clip it an leave it?As if it were a plant in the aquarium or should I time them for perhaps 2 minutes and then take it out? Then if I do the timing.. Throw away the remainder?

Also one day I got up an noticed one of my goldfishes mouth looking deformed. It is no longer oval shaped like that --> [ ]
lol @ my drawing. but it looks more like this --> () and it has trouble eating flakes so i need to cut them really small for it. The other is fine though.

Do you know what might have caused this? Should I be wondered about the other one? Is this a disease or something? It should be noted that its behavior hasnt changed. it doesnt look or act sick. and when it sees me it usually pushes at leasts its head out the water begging for food. It still does that. It however doesnt look for food at the bottom much anymore I guess because it cant suck on the gravel anymore cuz its mouth is jus too small

Thanks much in advance

Answer
Hi Kami!
Yes, you clip it and leave it unless you can hold it perfectly still for a long long time.
If it is deformed, then it could probably be mouth fungus. Don't add Aquarium Salt in the water IF you have snails or scaleless fish. To treat this, try getting the API Stress Zyme, Stress Coat, and the Tetra LifeGuard. These items are available in your local petshop and should help speed up and improve your fish's recovery.
Hope this helps!
~Sam