This disclosure provides fluidic devices and methods for performing a bioassay, for example bioassays performed on zebrafish. The disclosure provides various fluidic devices for performing a bioassay that include a sample chamber in fluid communication with an air valve; and a bioassay channel that can include a first bioassay region, for example for studying zebrafish in early stages of development and a second bioassay region, for studying zebrafish in later stages of development. The first bioassay region and second bioassay region can be defined using pillars, such as a first and second array of pillars. The fluidic device can have additional structures that are provided herein. Also provided herein are sample loading manifold devices for loading zebrafish embryos into fluidic devices and reagent delivery manifold devices for delivering reagents to fluidic devices. Furthermore, methods using any or all of the devices are provided.