Killifish are a special group of egglayers, often very colourful and interesting. Some of them are annuals and only live through a season- they lay their eggs in puddles that then dry out, the parents die and the eggs hatch at the next rains. This requires a special breeding technique in the aquarium; you can collect the eggs and keep them in peat. Killi enthusiasts often exchange eggs through the post. Other killifish live longer and breed in more conventional ways.
But there are lots of other egglayers. IF you are looking for something guppie-sized, cherry barbs might be a suggestion. A trio (2 f, 1 m) or a pair. Or if you have a little space, you could do danios. Condition with livefoods and remove parents after spawning, or they will eat the eggs. Another option is corydoras: 2m, 1 f is the best ratio here, again, condition with livefoods and remove parents after spawning.
