Could Anybody Suggest What Is Wrong With These Fish?

[Ellieabbott4]

my dwarf gourami had a small ulcer on its mouth and a small one on the side of its head, its eating fine and doesnt seem bothered. but also my peppered cory has got what looks like a bump or an ulcer on it and its very sluggish and its breathing is slow. i have tested my water and its all fine....i was going to seperate them to my spare tank but my 3 day old guppy fry are taking up the tank. im not sure what to do with these two fish, what could be wrong? what would the best course of action be?
 

 

 

 

 

 

[TallTree01]

What is the actual readings? How big is the tank? How is the feeding? What fish are in the tank? Is it heated? Is it filtered?have you put anything in the tank recently e.g rocks?
If you answer these I may be able to help you.

 

[Lunar Jetman]

As above. The first course of action would be a water change but check the stats first which may well give you an indication of what it going wrong.

 

[Ellieabbott4]

these are the readings:
 
gh: 120
kh: 240
ph: 7.5
nitrite: 0
nitrate: 20
ammonia: 0
 
the tank is 90l and has been set up since november last year. its heated and filtered. the feeding is fine. i recently added two female gourami and a bamboo shrimp.
 
also in the tank is roughly 15 guppies, 
1 male gourami,
2 female gourami,
1 bamboo shrimp,
4 cherry shrimp,
1 albino cory,
2 peppered cory
4 apple snails

 

[This Old Spouse]

As suggested, complete a water change, and make it at least 75%. How recently did you add the other fish?

 

[Ellieabbott4]

I just done a massive water change ( probably at least 75%) on Thursday as the water was really cloudy. The new fish have been in there about a week. Would it be wise to do another huge water change?

 

[This Old Spouse]

Why was the water really cloudy? And yes, you should do another big water change. What kind of water test are you using?