I've made private arrangements with my brother to take my dogs, if anything should happen to me and my husband. Fish are another matter entirely, at least in my family.
I'm pretty sure what would happen is that the fish would all be given away on freecycle.org and the tanks sold. At that point, it's kinda out of my hands.
75: blood parrots, featherfin cat, emperor tetras, turquoise rainbowfish, BN plecos, japanese trapdoor; 46: WCMM, gold inca snails, ghost, bamboo & amano shrimp, kuhli loaches, rummynose & ember tetras, endlers, platies, flame gourami, guppies; 16: pygmy, peppered, loxozonus corys, otos, assassins, RCS ... ~ Research PRIOR to purchase.... ~