Help!!

[hils]

5 weeks ago I set up a 15 gallon tank to breed my honey gourami's. It was very successful with loads of babies.
I went away when they were 2 weeks old and just asked my neighbour to feed them and nothing else as I know they are sensitive to air temp changes and water etc..
The tank is cling filmed, with a sponge filter, a few potted plants and no substrate.
I have come home to 4 survivors (I'm surprised there are any!), the tank is understandably filthy with algae and needs a good clean.
I'm scared to clean it and change the water in case I kill the remaining ones.
But, there is ammonia in the water!
Ph- 7.4
Am- 0.25-0.5
Ni- 0
Na- 0
Before I went away there was no ammonia, no nitrites and some nitrates.
Should I scrape the algae from the sides and the bottom and change some water? How much?
Shall I turn on a manual filter?
I really don't want to kill these guys, but the ammonia will anyway right?

 

[hils]

 

[livefishguy124]

your water seams pretty good i would yes clean algae, and then since you are worried about the water, do small water changes every day.

 

[sinibotia]

How sure are you about the ammonia reading? I tend to find that I always think a 0 reading looks a lot like a low level reading, but after a while.... my fish just aren't acting like there's constantly ammonia.

How do your fish look? If they look ok, it might just be an iffy reading. Otherwise, I'd do a big water change or add a double dose of prime.

Personally I don't let people touch my fish tanks when I go away. They can go a lot longer than we think without being fed.