Wow! Can't get a feel for how large the tank is. But if he's lived this long I'd imagine he's doing fine He may well outlive his owner
The marine biologist needs to stick to marine fish! A 15" and 2lb goldfish is not that exceptional. There are brown goldfish (stocked as Crucian Carp) are in many waters all over the country and can get to nearly 6lb! I've had goldfish over a foot in my pond in the past. The only bit that's exceptional is that it's grown to that size in a tank.
Aren't goldfish and crucian carp a different species? I read somewhere that there was a danger that true crucians were being wiped out because they were inbreeding with goldfish that people had 'disposed' of in public lakes/ponds.
The Crucian Carp (Carassius carassius) is a member of the family Cyprinidae as is the Common Carp and Goldfish, and it has seen a general demise over the last 20 years in this country, mainly i beleive to due it's sensisivity to pollution but it has been known to interbreed with our Common Carp in the wild,
Goldfish and crucian carp are two different species, both in the genus Carassius (golfish C.auratus, Crucian, C.carassius) They can interbreed to form fertile hybrids as they are very similar species that don't usually interbreed as they have totally different natural ranges which we have messed up completely by releasing millions of goldfish into waters up and down the country, some knowlingly released as goldfish but most are brown goldfish sold as Crucian carp that have been stocked in waters and then have interbred with true Crucian's already there. As such the British Rod caught record will only be accepted from waters where the purity of the stock is assured which I believe is about 5 waters in the country! Both species will also cross with common carp (or any of the many variations such as mirror, leather, koi, ghost etc.). These form hybrids that are fully or partly infertile and are often called 'F1 carp' when stocked into lakes. They get to a little over 10lb I think. Crucian carp are very tough little fish that have even been known to survive in the mud of almost dried up ponds! I have had one that got stuck in a plant pot (unknown to me) while I cleaned my old pond out) for about 5 hours and I thought he must have died and disappeared. When I put the plants back in the pond full of freezing tap water he swam out looking fine! Their two majors threats are hybridisation (by far the main threat) and the loss of the small ponds where they can thrive without being outcompeted by more aggressive species such as common carp.
