<P> A tuna is a saltwater fish that belongs to the tribe Thunnini , a sub-grouping of the mackerel family ( Scombridae ) . Thunnini comprises fifteen species across five genera , the sizes of which vary greatly , ranging from the bullet tuna ( max. length : 50 cm ( 1.6 ft ) , weight : 1.8 kg ( 4 lb ) ) up to the Atlantic bluefin tuna ( max. length : 4.6 m ( 15 ft ) , weight : 684 kg ( 1,508 lb ) ) . The bluefin averages 2 m ( 6.6 ft ) , and is believed to live for up to 50 years . When canned and packaged for sale , the product is sometimes called tuna fish . </P>
<P> A tuna is a saltwater fish that belongs to the tribe Thunnini , a sub-grouping of the mackerel family ( Scombridae ) . Thunnini comprises fifteen species across five genera , the sizes of which vary greatly , ranging from the bullet tuna ( max. length : 50 cm ( 1.6 ft ) , weight : 1.8 kg ( 4 lb ) ) up to the Atlantic bluefin tuna ( max. length : 4.6 m ( 15 ft ) , weight : 684 kg ( 1,508 lb ) ) . The bluefin averages 2 m ( 6.6 ft ) , and is believed to live for up to 50 years . When canned and packaged for sale , the product is sometimes called tuna fish . </P>
how many different types of tuna are there
how many different types of tuna are there
fifteen
fifteen