I have no ruler but these nigripinnis seem pretty small. That may also be my fault.
On the gardneri, I'm not sure as to why. You seem to be giving them better care than me. Mine are in a 2.5 gallon critter keeper with water 7.5 GH/KH of 8(just what comes from the tap). Fed micropellets, normal fish flakes, blackworms, daphnia, earthworms. No filtration, but 80% water changes about once a week. Are your gardneri also 'Misaje'? I can't really judge the color intensity on my fish but it does change alot. In some lighting conditions the male will look almost brown till the light hits his sides correctly.
Here's some photos of the nigripinnis. Let me know what you think. I heard from someone who saw the breeders that this isn't a very good strain of nigripinnis. Small, not very black, and not many spots compared to better strains.
The spawning container (2 liter soda bottle).

Today I stuck both males in to see what would happen. Male on the left ended up victorious after intense displaying and some fighting, but nothing too serious. Impressive since he was the second male introduced after the first male had 2 dives with the female. Soon as he was in the first immediately challenged him. Afterward I removed the first male and left the male on the left in with the female. Guess I will be using him most frequently for breeding from here on out. Perhaps a way of selecting the better fish?



Dominant male, now trying to convince the female to give just a few extra eggs. He would stick himself into the peat head first waving his tail and if the female was convinced she would do a headstand beside him and they would both "dig" into the peat.

Apologies about the photo quality but taking photos into a soda bottle using a desk lamp for lighting(hence the yellow/green look) doesn't work to well. In life the fish are a kind of purplish black with green or blue irridescence and blue spots.
Straightjacketstar: Nice Fundulus you've got there! Mummichog especially.