Almost all species scatter their eggs and don't protect them. In most bodies of water, even ones with piles of gambusia, those species are still able to reproduce with the right habitat. You may need to research how those species spawn and try to improve on what they need.
And yes, HBG are very aggressive and will readily eat the FHM in short order. About how many HBG would you say are in your pond?
Tarpon and snook when young are fast growers, I would think they should be putting some serious size on. Did you catch them in the wild and transfer them to your pond or were you able to source them from a local hatchery?
