Thinking about your big niece, have you ever considered inviting her over
and cooking escolar? It's a fish which is okay to eat in small amounts, but
the wax esters in its muscle meat will cause gastrointestinal problems if
too much is eaten. From the Wikipedia article on escolar:

"The gastrointestinal symptoms, called 'keriorrhoea', caused by these wax
esters may include oily orange diarrhea, discharge, or leakage from the
rectum that may smell of mineral oil. The discharge can stain clothing and
occur without warning 30 minutes to 36 hours after consuming the fish. The
oil may pool in the rectum and cause frequent urges for bowel movements due
to its lubricant qualities and may be accidentally discharged by the passing
of gas. Symptoms may occur over a period of one or more days. Other symptoms
may include stomach cramps, loose bowel movements, diarrhea, headaches,
nausea, and vomiting."

"To minimize the risk of symptoms, strict control of portion size is
recommended as well as preparation methods that remove some of the oil (e.g.
grilling). Portions should be no greater than 6 ounces."

Surely your big niece *could* limit her intake to six ounces...couldn't she?

Bob