How to generate speech with Fish Audio: API, Python SDK, and self-hosted S2-Pro

Fish Audio provides both a hosted text-to-speech API and downloadable Fish Speech model weights, with models including the production-oriented S2.1 Pro, a free development tier, locally runnable but non-commercial S2-Pro, and the expressive Drama 3. The hosted API supports cURL and Python SDK use, selectable library voices, reusable configuration settings, emotion tags, instant and persistent voice cloning with consent, and HTTP or WebSocket streaming for low-latency applications. Pricing is based on UTF-8 bytes rather than characters, while concurrency limits depend on prepaid spending; users must also account for model-default behavior, limited output formats for telephony, and S1’s planned retirement at the end of 2026. Running S2-Pro locally requires substantial hardware, typically a 24 GB NVIDIA GPU, and is constrained by licenses that restrict the weights to non-commercial use and limit commercial deployment of the code, especially as a hosted service. The comparison with AssemblyAI-TTS-1 presents Fish as better suited to expressive, creator-focused speech applications, while AssemblyAI is positioned for voice agents needing faster streaming, stronger code and address pronunciation, telephony encodings, flexible concurrency, and US or EU processing.

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