Cultural problems related to poor root health/ inhibited root function - almost certainly due to too much water in the soil and/or a high level of soluble salts in the soil solution. Because the leaf tips aren't involved, it's probably a combination of an inappropriately water-retentive soil and a too heavy hand on the watering can.

Al

Thanks, Next week I repot it.
Any ideas about the small plant?

You need to remember these plants are epiphytes, usually growing up in trees, and sometimes on rocks, but generally without any soil and roots exposed to air. They're even quite high up in trees where they'll dry out a lot while waiting for the next shower of rain. This is the sort of environment you need to try and replicate, or compensate for, as much as possible. It's better to have a porous potting medium which you water more frequently rather than a heavy soil that retains a lot of water. They don't like water stagnating around their root system. You could even plant it in wood or bark chips but that would require more frequent watering. Tap water varies tremendously in quality (and contents) and can be detrimental to ferns. Rain water is far better if you have access to it.

You're right about the small one also being an Asplenium. They have produced so many hybrids and variations on them that it very difficult to get a name for them. I got one very similar to yours, the label just said "Fern". Knowing that it's an Asplenium is about the most I can hope to know about what it is.

Thanks, I'm gonna repot it to semi-hydro. hope it helps.

hi, i'd like to ask how your plant is doing since you repotted because i'm having thesame problem. thanks .

It is doing great, there are 2 new healthy leaves. Tapla was right, it was overwatered and the soil wasn't a well-draining one.