Please answer the Trouble in the Enclosure questions so that we have all the background info.

Those are some pretty significant injuries. He isn't just missing claws he is missing entire toes. Do you know how this happened? You say you just moved him into this setup. What was he in before? Did you use a net to transfer him?

There feet (especially the webbing) is very delicate and can be damaged by handling or by sharp edges in the tank. Can you post a recent photo of the feet? I don't want to recommend antibiotics unless there are signs of infection. It's tough to tell from the photos you posted.

You need to fill his tank the rest of the way. That will greatly reduce the water disturbance from the output of the filter and will give him a lot more swimming room. As long as you have a cover on the tank there is no reason to limit the amount of water.

What do you feed him? Have you always had gravel on the bottom? We recommend bare or sand-bottom tanks since gravel is a risk of impaction if the frog mistakes a rock for a piece of sinking food. But if you've had success with gravel for 21 years I'm not about to tell you to remove it.

Do you keep the hood light on the tank? Did he always have a light? These frogs come from murky wetland habitats and aren't accustomed to such bright conditions. This kind of lighting causes a lot of stress. Either keep the light off or add some large artificial plants (floating or anchored) to provide shade.