its easier than a tropical marine tank, but keeping it cold is the biggest problem. i had a 50-ish litre cold tank for a while, but had a hard time keeping the temp down. was fun, those blennies have alot of character, they will dance for food remember those critters get a 100% water chance twice daily in nature too - long term you would need to sort out feeding, not sure what all those animals eat in the wild.