The direct answer for finding a guppy-experienced vet
A vet for guppies is found by searching for fish experience in general rather than guppy experience in particular, because almost no practice advertises by individual small species. Aquatic veterinary association directories, exotic-animal clinics, and university exotic services are the places where vets who examine pet fish actually work. Phone the promising practices and ask the precise question: does the vet see small tropical community fish, and can a sick guppy be assessed? Some will say yes readily, some will offer a consultation based on water results, photographs, and the history of the group, and some will decline, which is itself useful information. Tropical fish shops that breed or import guppies, and local aquarium clubs with livebearer keepers, usually know which of those answers each nearby practice gives.
What realistic guppy care from a vet looks like
Go in with honest expectations, because a guppy's size shapes what a vet can do. Examination is visual and often happens in the transport container, water testing forms a large part of the consultation, and questions about the whole group matter because guppy problems frequently run through a breeding colony rather than one fish. A knowledgeable vet will ask about stocking, water change habits, recent new fish, and whether others show the same signs, and may discuss examining a very sick fish more closely to protect the rest of the group. That group-level thinking is a mark of real experience with small tropical fish, not a lesser service. What you should not accept is a practice that dismisses the fish as too cheap to bother with; price has nothing to do with whether advice can save the rest of your guppies.
Routes that work when listings fail
General search results bury fish vets under dog and cat clinics, so work the specialist channels in order. Start with the aquatic veterinary directory for your region, then exotic practices within the distance you could realistically drive with a fish in a container. Ask the strongest tropical fish shop in your area who treats their stock, and ask the same question in a local aquarium society or livebearer group, where guppy breeders often keep a shared list. If every local route fails, ask whether a fish vet further away offers remote consultation using your water results, dated photographs, and video of the affected guppies swimming.
Getting set up before a guppy emergency
Guppies decline fast, so prepare the contact and the method in advance. Ask the practice how to transport a guppy, which usually means a sealed bag or container of tank water kept warm and dark, plus a separate water sample for testing. Keep your latest water test results written down, along with stocking numbers, recent additions, and when the first sign appeared in the group. Register with the practice if it offers registration for fish patients, and confirm how urgent fish cases are raised out of hours. None of this takes long, and all of it is much harder to assemble beside a tank of fading fish.
Filing the contact where it will be found
A fish vet is rare enough that losing the details means repeating the whole search during a crisis. Keep the practice name, number, transport instructions, and out-of-hours guidance in a single record, and note the backup practice as well, since this small field changes personnel often. If you breed guppies, add the vet's group-level advice to the same record so future outbreaks start from informed ground. Share the details with anyone who looks after the tank while you are away. Listing the practice in KinsLe Pet Services Directory keeps it among the local pet services you trust, retrievable the moment a guppy problem appears.