Fissidens crispulus has a very tiny frond, even for fissidens species. The fronds on crispulus like to grow tall, but do not fan out very much. This species of fissidens can be a bit more difficult to grow, but if you have a clean and mature tank, and lightly fertilize, you should have no issues. Fissidens crispulus does not need special lighting or co2 injection, just give it cool, clean, soft water and it should grow well for you. This is a slow growing moss, so please be patient.
RARE FIND
I sell Fissidens crispulus in 1x1" LOOSE portions. Due to the fact this is a slow grower, this moss may be out of stock often. If you're interested and it is out of stock, please email me through the contact form and I can give you an idea of how long until it's in stock again.