In this thesis, I present a set of interlocking biological and technological developments: in Chapter 2, I will argue that a class of glial cells in the larval zebrafish is structurally and functionally homologous to astrocytes, which have been intensely-studied in mammals. This finding is of interest because the larval zebrafish is a model organism that enables a uniquely expansive set of high-throughput, high-resolution experiments for probing the vertebrate nervous system, but these advantages have hitherto been leveraged exclusively for studying neuronal cells, with no consideration for glia. Chapter 3 presents evidence that zebrafish glia can participate in behaviorally relevant computation, which builds on and demonstrates the arguments of Chapter 2. The biological data I present in Chapters 2 and 3 would not be possible without an ecosystem of tools for gathering and analyzing functional imaging data via light microscopy. Chapter 4 presents a sorely-needed addition to the functional imaging toolkit: a simple technique for vastly accelerating data analysis of large functional imaging datasets.