I just started feeding frozen gel food to my guys for ongoing sbd problems. The cube is way too big for one meal for them (I am starting out by feeding very small amounts) and I was wondering if it is ok to keep the remainder of the cube in the fridge once it has been thawed and a piece cut off and used. If so, for how long do you think it would be ok to use?

Are you just leaving it open or keeping it in a sealed container? I don't think I'd trust it more than a few days either way really. What's in the food?

Right now I just have it open in a paper cup but am wondering if it is ok to use it for a few days?

It is Ocean Nutrition Formula One Frozen Food and these are the ingredients:

Ingredients: Shrimp, krill, gel binder, spinach, clams, krill hydrolysate, sardine meal, plankton, salmon egg oil, squid, kelp, lecithin, casein, paprika, canthaxanthin, cod liver oil, astaxanthin, vitamins (choline chloride, ascorbic acid including stabilized Vitamin C, Vitamin E supplement, niacin, thiamine mononitrate, folic acid, calcium pantothenate, riboflavin, menadione sodium bisulfite complex, Vitamin B-12 supplement, Vitamin D3 supplement, beta-carotene supplement, biotin), amino acids (dl-methionine, taurine, lysine), and trace elements of manganese sulfate, zinc sulfate, copper sulfate, and sodium selenite.

With all that seafood in it it probably gets bad pretty quickly. Is there no way to cut off what you need without thawing out too much? Then you can just keep the rest frozen instead.
I would definitely opt for keeping it in something covered though.

You are tight, thanks. I just did manage to cut a bit off of the frozen cube and keep the rest frozen. I am trying to give very small amounts a couple times per day.