I have been keeping freshwater fish for quite some time and I'm always mesmerized by how fascinating and resilient these creatures are. The oldest freshwater fish I had was a Plecostomus, who I fondly named "Spike". Spike lived for 15 years, considerably exceeding the average lifespan.
A primary factor to Spike's long lifespan was attributable to the care and maintenance of the water conditions. Consistency played a huge role - frequent water changes and maintaining the right pH level were part of the regular care. Diet was equally essential. Spike was fed a mix of sinking pellets, plus the occasional treats of blanched spinach and peas.
I feel compelled to share - longevity largely depends on the species, environment, and proper care. Some species are known to be long-lived, such as Koi and goldfish under excellent conditions can live for decades.
Overall, keeping freshwater fish can be a rewarding experience, but it does come with the responsibility of providing proper care and optimal living environments to ensure their health and maximize their lifespan. Remember, a well cared for fish is a happy fish!