Very well could be. What do you consider a serving to be ? Those portion packs are intended to keep the rest of the package fresh more so than being a suggested feeding amount. You could probably get by feeding 1/3 of a cube a day for a few small puffers.2 days ago my 10G tank was great. After adding a few puffer fish I started feeding frozen food as I was told they won't eat dry foods. I bought various frozen foods and have since fed them 2 servings of brine shrimp.
Today my tank has a thick oily substance floating across the top, enough to stop air getting into the water. Also the smell is horrendous!!!
Is this the frozen food causing this?