> ## Documentation Index
> Fetch the complete documentation index at: https://docs.metastreams.io/llms.txt
> Use this file to discover all available pages before exploring further.

# chain.nativePrices

> Streams the USD price of each chain's gas asset.

Streams the USD price of each chain's gas asset: SOL on `solana`, ETH on `base` and `robinhood`, BNB on `bsc`.

Subscribe on an open stream connection. See [WebSocket streams](https://docs.metastreams.io/streams/overview.md) for connections, frames and reconnection.

## Filters

**chains** `string[]`

[Chain slugs](https://docs.metastreams.io/concepts/chains.md) whose prices to send. Omit it or send `[]` to include every chain. `arc` is accepted, but its gas asset is USDC, so it receives no updates.

`{}` sends the price of every chain. Each subscription uses one unit of the [address limit](https://docs.metastreams.io/streams/filters.md#address-limits), whatever its `chains`.

## Message format

Each update's `data` is the price of one whole unit of one chain's gas asset. It has the same row shape that [Native prices](https://docs.metastreams.io/reference/rest/native-prices.md) returns, and `price.native` is always `"1"`.

An update is sent for each chain about every 10 seconds, whether or not the price changed. Each update counts against the organization's [credits](https://docs.metastreams.io/concepts/errors.md#credits), so a `{}` subscription uses about one credit per chain every 10 seconds. List only the chains you need.

Keep one price per `chain`, choosing the row with the later `observedAt`.

## Initial snapshot

1. Subscribe.
2. Read [Native prices](https://docs.metastreams.io/reference/rest/native-prices.md) with `chains` set to the subscription's chains.
3. Merge the REST response and the updates using the rule above.

A chain with no price yet has no row in the REST response. Its price is sent with the next update.

## Errors

| Code | When |
| - | - |
| `UNSUPPORTED_CHAIN` | Unsupported slug in `chains` |
| `VALIDATION_ERROR` | An unknown filter field; an exceeded [subscription limit](https://docs.metastreams.io/streams/filters.md#address-limits) |

```json Subscribe theme={null}
{
  "action": "subscribe",
  "channel": "chain.nativePrices",
  "filters": {
    "chains": ["solana", "bsc"]
  }
}
```

```json Update theme={null}
{
  "type": "update",
  "channel": "chain.nativePrices",
  "subscriptionId": "8c1d2e3f-4a5b-4c6d-8e7f-9a0b1c2d3e4f",
  "data": {
    "chain": "solana",
    "asset": "SOL",
    "price": { "native": "1", "usd": "178.42" },
    "observedAt": 1789632015120
  }
}
```


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