Eye colours, except when explicitly stated for a species, can be any colour except for extreme black or extreme white. They can be unnatural colours without any need for an item or inherited colours. While tsabhua pupils are generally slits, belemoid pupils are more often than not round. They both can expand to be quite circular in reaction to light or emotions but there should always be some sort of iris colour visible.
Heterochromia, regardless of complete or segmental, is also freely available for any colonist, unless there is a restriction on the species.
Albino colonists should have eye colours from the following general colours: red, pink, or blue. Also, keep in mind that the skin colour can peek through fur at thin points such as nostrils and toes.