Fish Audio, an AI voice company originating from the open-source Fish Speech project, has secured a $52 million seed round led by Coreline Ventures and Capital Today after reaching $21 million in annual recurring revenue and 8 million users. Founded by former Nvidia researcher Shijia Liao, the company launched its S2.1 Pro voice model, which supports text-to-speech, voice cloning, voice agents and 83 languages, and made it available through a free API under a fair-use policy. Its March release included open weights, fine-tuning code, an SGLang-based streaming inference engine and self-hosting support. According to Artificial Analysis, S2.1 Pro achieved an Elo score of 1,153, ranked 13th among text-to-speech models, processed 56.3 characters per second and supports natural-language emotion and prosody control. Fish Audio said its own blind listening tests favoured S2 Pro over models from ElevenLabs, Inworld and MiniMax, though the evaluation was conducted internally. The company now competes with ElevenLabs and Cartesia.