Follow-Up to my Blackmoor tale :-(

As promised, here is the follow-up: Before I could even order the
recommended gel-based food, one of my two black moors died. My husband went
to the pet shop and bought sinking food, thinking we could try that before
ordering the gel based food off the internet (because the price was
approximately $30 + shipping). That was only a few days ago. Initially, it
seemed like the other fish was doing better, but that one is now dying as
well. I have asked my husband to please not replace these fish. I am
thinking a betta may be a better choice. I would like an oscar but our tank
is only 10 gal, and the oscar would outgrow that in a few months (or
sooner).
Best regards,
---Cindy S.