Goldfish, sucker fish die suddenly

It appears that larger fish cannot survive changes in temperature. In August, the rains had stopped for a few days and both the gold fish and sucker fish appear to have died quickly and suddenly .
The reason for their death is not known, the fish had lived for more than 6 months without any major problem
However the Fighter Betta fish has survived and completed 1 year in a small bowl indicating that they are very hardy
The guppies,platyfish and neon tetra are surviving

Kindly note that the 10 google, tata sponsored fraud R&AW/CBI/indian intelligence employees faking a btech 1993 ee degree especially slim goan obc bhandari panaji pampered prostitute R&AW employee sunaina chodan 2013 bsc are not associated with the website as they do not spend any money online, on fish and do not do any work online, though the powerful top NTRO, CBI, indian government employees receiving SEX and other bribes continue to make fake claims as part of the never ending google, tata masterminded online fraud since 2010.