What is the minimum requirement of a figure to be in your main collection

[JimoAi]

For me, any animal above 24ft (720cm) will be in the 1:36 scale and all adult animals in my collection must be minimumly sexual maturity size in their specific sale (example, the Papo whale shark is 25cm when stretched out, it represents a 30ft individual)

[Isidro]

I think this question has been asked as a thread at least once in this forum and maybe probably more...
Anyway, different collectors have different standards for include animals in their collections. I don't have a main collection but just a collection, a single one, and the animals that don't qualify for it just get out of it, becoming decoration for my book shelves or being stored in boards or trading them for other things or whatever.

The criteria for include an animal in my collection are:
1) It must be a species that I don't have already. My collection is strictly synoptic and no more than one individual per species is allowed. The extreme of this is that I don't accept a plains zebra in my collection because I have a quagga (same species).
2) It must be realistic.
3) It must be a real species (not fantasy figures).
4) It must be extanct or recently extinct. Enough recently for have taxidermized specimens that allow us to know the real colours of the animal for example. Dinos are not included, but thylacines are.
5) It must be a wild animal. Domestic forms are not allowed in my collection (dogs, horses, pigs, cows, etc)
6) It may not be in the same scale than my other animals but must be not with a very striking scale difference. I can accept my too big fennec fox and my too small cetaceans (the two extremes of my collection I think), but I would never accept a butterfly or a ladybug that is bigger than a cat for example.
7) I only accept adult animals. A tapir calf is very attarctive but cannot be included.
Animals must be individuals. As much I can accept some marsupials with a young in the pouch if it's unobtrusive to sight (case of CollecTA's wombat). But an emperor penguin with a chick in the legs, no, thanks.

[sirenia]

Decent interest in the species.

[Advicot]

Fits well scale wise with the other figures, for example I don't add Incredible Creatures by Safari as they are too big, however I make a couple of exceptions like their corn snake and Burmese python
Decent realism, I don't add figures that are cartoony, but 90s Puppy in my pocket I can deal with (the current flocked versions are horrendous)
Preferably new species, however I do like having herds of zebra, giraffes etc

Pretty much anything that catches my eye and is of an alright scale with other figures. Recently I have been a lot more accepting with size! 

[JimoAi]

Juvenile animals must look vastly different to adult . For example, emperor angelfish young are allowed but not a lion cub

[BlueKrono]

My figures must be larger than microscopic size. I do have a few that are as small as my fingernail.

[Isidro]

Well, I actually consider that a lion cub is substantially different from an adult, but I see what you mean Only few vertebrates have juveniles so strikingly different from the adult as the emperor angelfish, but if you come to insects then you have plenty to choose (all the holometabolous ones, so the majority of insects)

[sbell]

It has to be a figure that I want.

Some categories are more important to me than others. Among modern animals that includes osteichthyans, especially freshwater, in particular ones that are unusual, primitive or fit into some of the clades that I am most interested in; unusual chondrichthyans; agnathans (so, not much there!), mammalian fissipedia (other than basic ones) but especially hyenas & viverrids; other weird mammals if I don't have them; caudate amphibians; the occasional interesting squamate or crocodilian; some inverts that stand out...pretty much when something appeals to me for some reason.

I've gotten far pickier lately. Not enough room for everything anymore!

[Loon]

I want my figures to look accurate. I don't really care for artist's takes on animals; this is an issue that plagues the prehistoric toy market (looking at you, Papo). I suppose that falls under "realism", though, that term's so loosely thrown around, I figured I'd give a specific definition.

Another thing I look for are figures of species I have an interest in. It could be a specimen I saw at a museum, or just an animal I enjoy learning about. There could be an incredibly accurate figure of a certain creature, but if I have no connection with it, I have no interest. This was a mistake I made when I got back into collecting, I had so many dinosaurs, and half of them I wasn't even that familiar with.

Finally, and this is the last test for inclusion, space. I have a certain number of shelves and I really hate crowding them, so I try to limit figures to those that fit in with the themes of said shelves.