The smaller pair I've had maybe 7 months, the larger pair I think about a year and a half, maybe two years. The larger female had 'issues' for over two months before she'd feed on her own, while the male grew like a weed and ate the whole time (she's only put on 2-3" while he's put on probably 8" or more). They're not in the largest tank, but water params are fine and they will be upgraded once I move in the next couple months.