Generally, as dave says, knowing more is always a good thing. But in practical terms, spending a significant chunk of time on playing another instrument might or might not work out for you specifically. For example, if you have limited practice time available, expending a good chunk of it on learning to play another instrument might mean you can do less work on your primary instrument. For another example--not saying anything about you or anyone else personally--but if you play your second instrument badly, it's not necessarily going to help you on your primary one. OTOH, to the extent that another instrument gives you another and fuller perspective on music, on how to play, hear, feel, and understand things, then it could be a very good thing. I've played both guitar and bass for many years and feel that's been extremely useful for me, though I think guitar has helped my bass playing more than the other way around. As for your specific question, congas can be kind of hard on the hands if you really get into it. You might prefer to save your hands for the bass. In all honesty, I feel that understanding and being able to hear what's going on with other instruments may be more important for a bassist than actually learning how to play them. Don't get me wrong, I'd love to be able to play a dozen instruments fluently ... but I don't actually need to. For example, i can't play a drumset worth a dang and never could, but I've learned a bit about how drummers play and put a beat together, and that's been quite helpful. As ever, YMMV.