What could be a problem?

What kind of plants are they? (Aside from the Hygro, of course.) And what
kind of fish do you have in the tank?

If I had to guess, I'd say you bought plants that are not true aquatics. IME,
most of the plants sold in pet stores for fish tanks are not true aquatics. No
matter what you do, they always die in a couple of months.

The Hygrophila corymbosa is a true aquatic. But it's grown emersed, so it
might need some time to adjust to life underwater.





Leigh

http://www.fortunecity.com/lavender/halloween/881/