Q: How big does (fill in species) gar get?
Wild sizes are not an accurate indication of the captive size of the fish. Captivity poses challenges to a fish’s physiology that would not generally occur in the wild. Many different factors are involved with how big a fish will get and when it will get that big. This needs to be very well understood by the potential or current gar owner because of the fact these are generally large fish and they reach a large size rapidly. Each species is slightly different in growth rate. In general you can expect and should expect small juvenile fish to grow quickly to what is often referred to as a plateau size where growth will then slow. In general the following is a ballpark rough guide what you should expect:
Atractosteus:
Alligator gar (A. spatula): 15 to 24 inches first year. 5 foot average adult size
Tropical gar (A. tropicus) 12 to 15 inches first year, 2.5 foot average adult size (Unestablished)
Cuban gar ( A. tristoechus) 12 to 15 inches first year, 3 foot average adult size (Unestablished)
Lepisosteus:
Longnosed gar (L.osseus) 12 to 14 inches first year, 2.5 to 3 foot adult size
Shortnosed gar (L. platostomus) 12 to 14 inches first year, 2 foot adult size
Spotted gar (L. oculatus) 12 inches first year, 2 foot adult size
Florida gar (L. platyrhincus) 12 inches first year, 2 foot adult size
Hybrids are very much undocumented but have been shown to mirror the species crossed with an intermediate plateau point. For example the L. platostomus X A. spatula hybrids maxed out at 14 inches the first year. Actual adult size is unknown.
Again the above is a rough estimate and this will differ depending on several external factors such as diet, feeding frequency, water condition, frequency of water changes etc.