Does anyone know how much bioload zebra danios, tiger barbs, neon tetras, and dwarf gouramis have?
Kind of an odd question as there isn't really a unit of measurement someone can give you. They all have a reasonably small bioload, especially the neons. Male dwarf gouramis will fight badly and females are hard to find so that will effect how many you can have. The rest are schooling fish and need to be kept in groups of 6+ but are happier in larger groups so you should have as many as you can. All of those fish need 20 gallons minimum. The danios need a 30" tank minimum as they are very active.
It is impossible, as @BottomDweller said. You have to use your judgment there, and consider its mass. You can fit a lot of neons in the bulk of a goldfish, but then again, it isn't that simple. A goldfish has a different gut structure and produces a relatively different amount of waste - a huge bioload. A micro-predator like a neon has evolved a more efficient gut, so even gram for gram, you have a different bioload.
It's exactly why the one inch per gallon myth is a myth. An inch of tiger barb is a few inches of zebra, but there are so many other factors. Each species has its own bioload, at each step in its age/development.
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