@Westcoastperson Roundhouse Aquarium was tiny, like a nature center's visitor center, but they had some nice tanks. I got one lifer from it (Gibbonsia elegans, the spotted kelpfish).
As for other places, this was my 5th time in LA, so I'm running out of animal-related places to visit and I could use some recommendations.
@RatioTile
Well it’s tough once you’ve visited the major zoos and aquariums. There’s STAR Eco Station in Culver City which acts as a rescue and education center for exotic animals, might find some interesting reptile and bird rarities but I’m not too sure. The Reptile Zoo in Fountain Valley certainly has some reptile rarities. Bolsa Chica Wetlands Interpretive Center has some aquariums, Madrona Marsh Interpretive center has terrariums for California native herps and and invertebrates. Plus both of those places have great wildlife and bird watching during the right season. One other place that might yield some interesting species is LAX Aquarium store. They’ve always got some interesting species, they used to have a large shark tank with blacktips, horn sharks, smooth hounds, etc. but last time I was there they were renovating it.