Purpose: Being able to record zebrafish brain activity is essential to investigate and characterize the abnormal electrical discharges during seizure-like responses in epilepsy studies. The current procedure employed to record extracellular field potentials in the larval zebrafish forebrain is an adaptation of conventional extracellular recording techniques, using a patch clamp amplifier. In the present work, we aim to establish a protocol to obtain electrographic recordings of zebrafish with a simpler and more cost-effective setup for laboratories intending to implement this technique in their routine. Methods: Each zebrafish 7 dpf larvae was anesthetized and paralyzed with 400µM tricaine and 10µM d-tubocurarine. After complete loss of movement, the animal was placed in a lid removed from a 1.0 ml eppendorf tube filled with 1% low-melting agarose prepared with aquarium water. Fish was positioned horizontally, with the dorsal side exposed to the surface. Quartz/platinum-tungsten microelectrodes were attached to a pair of connectors and fitted onto a MN-153 Narishige micromanipulator. One electrode was placed slightly in front of the forebrain of the animal, and another in the agarose. Electrical activity was recorded using the RHD2000 Evaluation System (Intan Technologies®). We used a setup that includes an interface board connected to a host computer via standard USB cable, and to a small amplifier board via a 0.9m serial peripheral interface cable. To prevent external electromagnetic interferences, the setup was placed inside a Faraday cage. To validate the system, we performed preliminary recordings of larvae with and without addition of 30 mM pentylenetetrazol (PTZ). Results: To date, we have built a setup to record extracellular field potentials in zebrafish brain using a system that transform weak electrode signals directly into a digital data stream. Our pilot study showed high amplitude electrographic discharges in the animal exposed to PTZ compared to the control, starting approximately after 30 minutes of exposition to PTZ, with intervals of 5-10 minutes. Conclusion: In the present work, we described a cost-effective protocol for electrographic recordings on immobilized zebrafish larvae, as it does not require a patch clamp amplifier. We have accomplished stable long-term monitoring of brain activity in immobilized zebrafish larvae and we are currently working towards a characterization of the epileptiform discharges in order to study the seizure-like responses evoked by the convulsant agent PTZ. Since studies using zebrafish to elucidate the basis of seizure generation are still scarce, this study provides new tools to study the mechanisms underlying seizures in this model. Supported by Fapesp.