Plants Mysteriously Disappearing?

[AquaticHamster]

So I have a twenty gallon planted tank with probably six different kinds of low to medium light plants. I have plenty of fish, but none that would do any harm. I had a few snails, but I threw them out and haven't seen any since. But about a week ago I've noticed that one of my plant species has been disappearing? I'm not sure what its called exactly. I first noticed that half of one was totally gone and then a little one growing by it suddenly lost all its leaves and is now barely there at all. Just today I noticed another one of my larger ones has been attacked. It had growing leaves on it yesterday now suddenly today they're gone along with half the plant itself. My baby java ferns are also not looking too good. I'm just so confused on this because my tank is been doing so great lately and now I'm so upset. I worked so very hard to get my tank to where it is, and now something's making off with my plants.

Anyone have any idea what's going on?
 
Here are some pictures. My tank looks just awful now...
This is the plant species that is disappearing.

Notice how the outer layer of the stem has been eaten away.

Heres a pic of the tank.

 

[jocie1976]

I had this happen with a lot of plants that had smaller leaves. I had no luck with them at all. ALL of my fish were pecking at the plants and the leaves just kept disappearing. I gave up on small leaved plants in my large community tank and now only do plants with larger leaves. Is there anything floating on top of the water to suggest that this might be happening to you? How long has your tank been planted? Do the leaves look like they are melting off? Do you use fertilizers at all? How long is your photo period?
 
Now I do have a plant (don't know the name) with small leaves in my 20g with a Betta, 5 Cherry Barbs, 3 Green Cories and 2 Cherry Shrimp and it is just taking off. So much so that I have divided it 3x times already in 4 months. These fish are not bothering it at all.

 

[SO19Firearms]

Too much light and not enough CO2

IMO

 

[techen]

I agree, put a timer on those lights! Less surface movement for more co2