Ph, Ammonia, Nitrite, Nitrate Problem... Need Advice & Knowledge&#

[DreamertK]

Maximum Standard Length
6″ (15cm) body length and as much as 8″ (20cm) or more in height.

 
Usually long tanks are only 12" in height, and there would be 1-2" of substrate at the bottom. For angels you want to go with tall tanks or just larger tanks in general which would also be taller as well as longer. A 27g cube tank would be good for breeding purposes, but bigger is always better.

 

[Alasse]

15" height is the minimum for an standard angel tank, 18" height for veiltail type angels, and 3 adults is too much for a 20gal, i will hold 2 no problems + the guppies

 

[DreamertK]

Many people say that 30g is too small for a pair to be held in long term without being stunted. Sure it sounds fine, a few inches above and below the fish, but when you actually look at them in the tank then you realize how cramped it must be for them. But yeah, some angel fish are larger than others. I posted the measurement for the standard angelfish.

 

[attibones]

If you can't get a big tank any time soon, then you just need to rehome these fish. Only the guppies are suitable for your twenty gallon. Depending on how long you have had all of these LARGE fish, you may have already stunted them a bit. It is never a good idea to buy fish with the intention to get them the suitable home as they she. It almost never works out. You have to have the suitable size first. It's just responsible fish keeping.

 

[Alasse]

Many people say that 30g is too small for a pair to be held in long term without being stunted. Sure it sounds fine, a few inches above and below the fish, but when you actually look at them in the tank then you realize how cramped it must be for them. 

I've kept them in 15inch tanks long term with no stunting. They are not cramped either, they can swim comfortably and manoeuvre as needed. 
 
While taller is better if you can

15" for a standard is certainly doable

An example: This is an 18" high tank with approx 2" of substrate, and they have plenty of room to move in the 16inches left, even if i added another 2-3 inches of gravel
 

 

[DreamertK]

How long is that tank??

 

[Alasse]

That tank is 5ft L x 18" H x 20" W