user27384: I found this pump:
https://www.aliexpress.com/item/Free-Shipping-Ultra-quiet-DC-12V-3M-240L-H-Brushless-Submersible-Water-Pump-High-Qualtiy-mini/32472119699.html
Now, I want to control it from an Arduino.
Is this a good relay to use? 
https://www.pololu.com/product/2480?
I want to use a 12v battery for the pump.

user27386: I see people are recommending mosfets (which is the best option). Keep reading this if you still want to use relay. There are two kind of relays, mechanical and solid state. Mechanicals are cheap but they can be noisy (they make sound) also they have low life expectancy compared to solid state relays. On the other hand solid state relays are faster with everything else but they are expensive. Also you need to check voltage and max current rates before buying. 

user27110: About the relay, you can buy a low cost relay from aliexpress like the following one or other variant.
https://m.aliexpress.com/item/32392799916.html#autostay
It's well within your desired voltage and current  range and works readily with arduino.

27384: <p>I found this pump:</p>

<p><a href="https://www.aliexpress.com/item/Free-Shipping-Ultra-quiet-DC-12V-3M-240L-H-Brushless-Submersible-Water-Pump-High-Qualtiy-mini/32472119699.html" rel="nofollow">https://www.aliexpress.com/item/Free-Shipping-Ultra-quiet-DC-12V-3M-240L-H-Brushless-Submersible-Water-Pump-High-Qualtiy-mini/32472119699.html</a></p>

<p>Now, I want to control it from an Arduino.</p>

<p>Is this a good relay to use? </p>

<p><a href="https://www.pololu.com/product/2480" rel="nofollow">https://www.pololu.com/product/2480</a>?</p>

<p>I want to use a 12v battery for the pump.</p>
 27386: <p>I see people are recommending mosfets (which is the best option). Keep reading this if you still want to use relay. There are two kind of relays, mechanical and solid state. Mechanicals are cheap but they can be noisy (they make sound) also they have low life expectancy compared to solid state relays. On the other hand solid state relays are faster with everything else but they are expensive. Also you need to check voltage and max current rates before buying. </p>
 27110: <p>About the relay, you can buy a low cost relay from aliexpress like the following one or other variant.</p>

<p><a href="https://m.aliexpress.com/item/32392799916.html#autostay" rel="nofollow">https://m.aliexpress.com/item/32392799916.html#autostay</a></p>

<p>It's well within your desired voltage and current  range and works readily with arduino.</p>
