Yes, Java moss produces oxygen. Like other plants, Java moss produces oxygen as a byproduct of photosynthesis. During this process, it also reduces CO2 levels in the tank, thus making the water cleaner and healthier for other tank inhabitants.
Aside from oxygenating the water, here are some other benefits Java moss brings to your tank:
- Absorbs ammonia, nitrates, and nitrites from the water
- Acts as a source of food for certain omnivorous and herbivorous fish
- Provides hiding space for tank inhabitants
- Provides an ideal space for spawning