You could try those little peat disks that gardening places sell to start seeds with. You know, you add water and they expand into little "pots".
I wouldn't get just a bag of peat, but the peat disks for seedlings are sterilized. It will be messy, though. Make sure you have something like a felt filter bag to put it in and soak it really well before adding it. Your water will also turn yellowish or brownish, but the kind of fish that really need soft water like that.
try black water extract or prepared peat extract. you can salso make your own using ketapang (mangrove chestnut) dried leaves. soak them in water for a couple of days