We have had our kissing Gourami for about 4 years and just recently noticed a darkspot on the end of its nose. The spot has grown now to the size of a dime and I cannot find anything online explaining what i could be. The spot isnt raised at all, it's just discolored & the fish is acting normal however I just want to make sure it isnt infected, or if it is, how can I help it get better. Any ideas?