Unclear Minimum Tank Sizes

[ZephyrStarPlaties]

I own a few fish that have been kept in a large variety of tank sizes, and many sites have different opinions on what these fish can be kept in. Since many people on here seem reputable and give good advice, I was wondering what your thoughts were.

Ryukin Goldfish - 30 gallons for first one, 20 or 10 for each additional.

Dwarf Gouramis - 5, 10, or 15 gallons

Platy - 2, 3 or 5 gallons

I own all these fish, and was wondering what the right stocking really is.

 

[Fishy friend2]

For goldfish, the tank size matters more than the volume, as a 30 gallon high wouldnt be sufficient long term. while a long might be until it reaches 7 inches. Ideally you want to aim for a 4 (Length) by 15-20, by 15-20 height and width. usually in a tank if that size you would want to add atleast 20 gallons for each additional fish
Dwarf gouramis also love to have surface area so a standard ten gallon should do
platies are fairy active fish, that are very social and should be placed in a tank upwards of a 10 gallon standard

 

[Ruskull]

A single Dwarf Gourami is fine in a 10 gallon, a 5 gallon is too small in my humble opinion. A pair or even 1 male & 2 females need at least a 20 gallon. I would think Platies should be kept in groups so they can socialize and 3 would require a 15-20 gallon absolute minimum.

I don't know anything about Goldfish whatsoever.