A simple bag or tub, done properly for a guppy
A thick fish bag or a small rigid tub, filled with its own tank water and cushioned inside a dark insulated box, suits a guppy perfectly well for a short trip to a specialist. Guppies have no spines to puncture plastic and no jumping reputation to defeat, so this is one case where the ordinary fish-shop method works, provided the details are right. Fill the bag about a third with tank water and trap a large pocket of air above it before knotting or banding it, round out the corners so a guppy cannot wedge itself into a pointed fold, and double-bag if the journey crosses town. A rigid tub swaps the corner problem for a lid to secure, and either choice succeeds when the water is home water and the ride is dark and level.
Sex, pregnancy and who should travel together
Which guppy is travelling changes the packing more than the container does. A single male with flowing fins needs gentle water movement, because sloshing that would not trouble a short-finned fish can batter long finnage against the bag for an entire drive. A heavily pregnant female should travel alone in a slightly larger volume, with the smoothest possible ride and no male companions harassing her in a space she cannot leave, and her container should be the last packed and the first opened. Fry should not make a specialist trip in the same bag as adults at all; their size lets them be trapped, crushed, or simply overlooked when the specialist counts what arrived. Keep the travelling party as small as the visit allows.
Catching a guppy without the frantic chase
A guppy chased at speed around plants and ornaments arrives at the specialist already exhausted, and its faded colour then tells a misleading story about its health. Dim the tank light, rest a clear cup or the open bag against the glass, and guide the guppy in with one slow hand movement, letting it swim into the container rather than pinning it with a net. If a net is unavoidable, use a soft fine mesh and support the fish's weight in water inside the net instead of lifting it dripping through the air. Once bagged, place the guppy straight into the dark box, because a bag carried around the house in bright light while keys are found adds stress that the actual drive never needed to include.
Reading a guppy's colour on arrival
A guppy's colour is a useful travel report: males that arrive with their pattern still showing and fins spread have coped, while a washed-out fish clamped at the bag's bottom needs a quiet word with the specialist about how the journey went. Mention if a female has dropped fry in transit, if fins look newly split from sloshing, or if the fish is gasping at the surface despite a generous air pocket, since those details separate travel stress from the problem you booked the visit for. At home, float the bag to equalise temperature, open it away from bright light, and release the guppy into a calm corner of its tank before offering a tiny feed later. Noting the strain, companions and that arrival colour in KinsLe with Care Pass builds a travel record this guppy can reuse on every future trip.