Sort the guppies before you bag a single one
Guppies move safely when they are sorted first and travelled in small groups of their own tank water. Adults go in one bag or container, females heavy with fry in another if they are close to dropping, and loose fry in their own container, because a confined, hungry adult guppy will eat fry it would mostly ignore in a planted tank. Small groups also keep waste and oxygen use manageable in each bag. Counting roughly as you sort gives you a number to check against at the new tank, which matters with a fish this small and this easy to leave behind.
The fry problem hides in the old tank
Draining a guppy tank without a fry check loses fish silently. Fry shelter in plant thickets, inside filter intakes, in the corners of breeding traps, and in the last shallow water over the gravel, where they are nearly invisible against the substrate. Before the old tank is emptied, lift plants out into a bucket of tank water and inspect them there, run a fine net slowly through the remaining water several times, and shine a light along the glass at water level. Move the plants themselves in wet bags or buckets, both to protect the fry hiding in them and to give the adults instant cover when they are released at the other end.
Catching quick fish without exhausting them
Lower the water level first so the guppies have less room to sprint, then work with two fine nets, using one as a slow moving wall and the other to scoop. Chasing a single guppy around a full tank exhausts the whole group and raises the temperature of the room for everyone, so patience at this stage is practical, not just kind. Transfer each catch into the travel container promptly rather than holding fish in a small cup while you hunt the next one. Keep the container covered as you work, because a startled guppy can jump surprisingly well, and a fish on the floor during a move is rarely found in time.
Small water volumes change temperature fast
A bag of guppies carries very little water, and that water takes on the car's temperature quickly. Pack the bags upright in an insulated box with a soft barrier between them, keep the box out of direct sun and away from heating or cooling vents, and avoid opening it for checks that let warmth escape. On a cold day, a wrapped warm water bottle placed outside the fish bags inside the box can steady the temperature; never rest anything hot directly against a bag. Travel with the guppies in the passenger cabin, loaded last and unloaded first, and keep their filter media wet in tank water so the new tank cycles from established bacteria.
Release, cover, and the first feed
Give the receiving tank its plants and hiding places before the guppies go in, since cover is what settles this species after a move. Match the bag water gradually to the new tank's temperature, add small amounts of tank water, then release the adults first and the fry into the densest plant cover, ideally through a breeding trap or mesh box for their first days if adult tankmates are hungry. Skip feeding until the fish are exploring, then offer a small amount of their usual food. Watch for clamped fins, shimmying in place, or fish hanging at the surface, and ask an aquatic veterinarian or experienced fish shop for advice if those signs do not lift within a day. Keeping the counts, helper questions, and setup updates for the guppies in KinsLe Messenger means the whole move is coordinated in one per-pet hub instead of scattered chats.