Niles tend to remain skittish and very defensive. This is a tendency not a rule/law/absolute. Some niles will mellow out and become calm and tolerant. However, if one had to place a bet, the odds are stacked against a nile monitor becoming something calm and tolerant and dealing well with interactions. Niles are better off being observed rather than handled. If this will pose a problem for you when it gets bigger, then your best bet is to find it a new home now. Sadly, most ill-tempered niles end up being neglected and dying early. I would also counsel against getting a water. Although waters are more likely than a nile to become a calm and tolerant monitor that is also not a rule/law/absolute. That means you can end up with a very unpleasant water monitor. The most ill-tempered monitor I have ever had was a water monitor, and I have kept both niles and waters. Waters also tend to get bigger, which means an ill-tempered water has more potential to do some serious damage if it becomes upset.
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^x^ Bloodbat ^x^