This deck is awesome. Murlocs are awesome and adorable. Just listen to them mrgllglglgle. If you don't love murlocs, you will not gain the blessing of Underbelly Angler, the one true god of hearthstone. 

You can be  slow and fast with this deck because of underbelly, just when opponent finally thinks they have exuasted your resources you play the one underbelly and random murloc you must ALWAYS keep in your hand. So yes you must always keep one underbelly in hand if you don't have one on the field. Thanks to underbelly, you can use your unlimited murlocs to protect their god, or if you can you play bloodlust to make you tiny minions hit like trucks. You don't even have to include Scargil and Amalgam in your deck because you can sub them out for other murlocs or any other cards because you will probably get them from underbelly.

Finally, if you want you can swap lighting bolt for lightning storm.