Advanced format ruling
Maiden of the Aqua
Card effect (current official text)As long as this card remains face-up on the field, the field is treated as "Umi" (however there is no increasing or decreasing of ATK/DEF due to "Umi"'s effect). If there is an active Field Spell Card on the field, this effect is not applied.
Current rulings for this card are maintained by Konami.
Rulings data courtesy of Format Library — formatlibrary.com. Spotted an inaccuracy? Flag it in the Advanced forum — sourced change requests get reviewed.