Fish Audio S2 Technical Report
We introduce Fish Audio S2, an open-sourced text-to-speech system featuring multi-speaker, multi-turn generation, and, most importantly, instruction-following control via natural-language descriptions. To scale training, we develop a multi-stage training recipe together with a staged data pipeline covering video captioning and speech captioning, voice-quality assessment, and reward modeling. To push the frontier of open-source TTS, we release our model weights, fine-tuning code, and an SGLang-based inference engine. The inference engine is production-ready for streaming, achieving an RTF of 0.195 and a time-to-first-audio below 100 ms.Our code and weights are available on GitHub (https://github.com/fishaudio/fish-speech) and Hugging Face (https://huggingface.co/fishaudio/s2-pro). We highly encourage readers to visit https://fish.audio to try custom voices.
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Shijia Liao
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Yuxuan Wang
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Songting Liu
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Yifan Cheng
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2026-03-11T09:47:31.449Z
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Yifan Cheng
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Ruoyi Zhang
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2026-03-11T08:29:04.291Z
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Ruoyi Zhang
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Tianyu Li
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Shidong Li
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Yisheng Zheng
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2026-03-11T09:48:05.913Z
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Yisheng Zheng
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Xingwei Liu
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Qingzheng Wang
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2026-03-11T10:14:46.963Z
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Qingzheng Wang
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Zhizhuo Zhou
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Jiahua Liu
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Xin Chen
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Dawei Han
Fish Audio S2 Technical Report
We introduce Fish Audio S2, an open-sourced text-to-speech system featuring multi-speaker, multi-turn generation, and, most importantly, instruction-following control via natural-language descriptions. To scale training, we develop a multi-stage training recipe together with a staged data pipeline covering video captioning and speech captioning, voice-quality assessment, and reward modeling. To push the frontier of open-source TTS, we release our model weights, fine-tuning code, and an SGLang-based inference engine. The inference engine is production-ready for streaming, achieving an RTF of 0.195 and a time-to-first-audio below 100 ms.Our code and weights are available on GitHub (https://github.com/fishaudio/fish-speech) and Hugging Face (https://huggingface.co/fishaudio/s2-pro). We highly encourage readers to visit https://fish.audio to try custom voices.
Fish Audio S2 is an open-source text-to-speech system with multi-speaker capabilities, multi-turn generation, and instruction-following control through natural-language descriptions, utilizing a multi-stage training approach and production-ready inference engine.
text-to-speech multi-speaker multi-turn generation instruction-following control natural-language descriptions multi-stage training staged data pipeline video captioning speech captioning voice-quality assessment reward modeling SGLang-based inference engine RTF time-to-first-audio