(1) Catch some meatballs first, then count the number of fish and beef meatballs, write down the ratio of fish and beef meatballs, and repeat for many times. The proportion of fish and beef balls in hot pot can be estimated by the proportion of each group, and then the number of fish and beef balls can be calculated respectively by the number of fish and beef balls *** 100;

(2) Because the ratio of fish to beef is 13: 7,

Therefore, the probability that any meatball is a fish meatball =1313+7 =1320.