Check out my fish formula monarch deck post banlist?

Try to focus on a specific base. I would recomend use a water elemented base. Please try to focus on having around the same number of spells compared to traps. Try mirror force and scrap iron scarecrow for traps. This deck can really benifit from the spell card Umi or A Legendary Ocean. If you choose to use either spell cards than I highly recomend tornadow wall to prevent any battle damage. There is also some water Synchros and fusions that can be useful. My final piece of advice is to get the furry of the deep structure deck. Hope this helps.