Difficulties growing java fern

Sorry if I confused everybody. The java fern is no longer in the 25 gallon with the 6 rummies, gouramis etc. It has been moved into the betta and corydora tank where is receives more light (2 hours direct and 10 hours indirect sunlight from sun positioned at the window sill)
 
Wells its a betta tank. It is a 5 gallon tank with no heater or filter. It used to have a corner filter but I have taken it out as it keeps breaking the betta's bubblenest. I know bettas are tropical but it is doing perfectly well in there without a heater and the peppered corydoras are loving it.
 
I was intending on breeding the betta and yes I will get a a heater. And I only moved the corydoras into the 5 gallon as it was too warm in the 25 gallon. They were very stressed, lethargic with cramped fins in there. I will get a bigger temperate tank for the corydoras soon.

Anyway back to the java fern. What is wrong?
 
wait, what is the temp in the 25? Mine has gotten up to 85 without any issues, are you sure you don't have issues with ammonia?

Regarding the fern, I don't think there is much you can do. Might be lacking nitrogen (nitrates), try putting it in the 25 and see what happens.
 
Sounds like your 25 gallon gets very little light. Just indirect room lighting? Java moss is almost indestructable but the fern does need a watt per gallon, and more is better if you want it to look its best.
 
In the 25 gallon, it is now 26 C but two weeks ago it was at 29 C. The tank was so warm because it was used as a breeding tank for my dwarf gouramis. And yes I am sure that the taml is cycled. The tank has been up and running for a few months, - tank cycling in a month. (had tests kits to see process) I don't want to put the java fern back into the 25 gallon as this is where the problem started. I moved it into the betta tank to see if it would improve bu so far nothing.

No, the 25 gallon gets indirect sunlight as it is sitting next to a window. Gmh, I think i do need a light and will purchase one soon after I move houses.
 
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