You're about to attack the first area that has Camo Bloons in it. You should hold off attacking this tile until you're ready. A Centre Of Camo Countermeasures is required for most Monkey upgrades that can detect Camo Bloons.
~ Bloons Monkey City when the player is attacking a tile with Camo Bloons for the first time
Camo Bloons are very dangerous since most Towers cannot hit them. Any Bloon type can be a Camo, and so will all the Bloons that come out of that one. They can only be hit by Towers that can detect Camo Bloons, such as the Ninja Monkey. In an emergency, use Road Spikes to pop them.
In BTD5, Camo becomes a property of bloon along with Regrowth, meaning any bloon from a Red Bloon to a Ceramic Bloon can acquire Camo properties. MOAB-class bloons cannot be camos, nor can their children (though the D.D.T. is an exception along with bloons sent in BTDB Flash). They cannot be targeted by most towers. However, there are upgrades that can make surrounding towers and/or themselves able to see them, such as Sonar Beacon and Crow's Nest. Camo bloons first appear on round 24 in both BTD4 and BTD5.
If another tower targets a Bloon and a Camo Bloon gets in the way, the Camo Bloon will be popped. If a tower with piercing projectiles targets a Bloon in front of a Camo Bloon, both will be popped. Usually, all you need is one set of Road Spikes or a Pineapple to set off a chain reaction. Camo RBE: 11 (BTD4), same speed as a red.
The following towers and upgrades allow the tower and/or nearby towers to detect Camo Bloons:
In BTD5, Camo becomes a Bloon property: therefore their RBE can be from 1 to 104 unlike in BTD4. If a tower cannot see camo bloons, its projectiles will go straight through them without doing any damage to them. A camo bloon can also be Regrowth at the same time, making them very dangerous if you do not prepare, like in round 82.
The following towers and upgrades allow the tower and/or nearby towers to detect and also target Camo Bloons:
11 hits are needed to pop the entire Camo Bloon in BTD4, yet one bunch of Road Spikes (10 spikes) can pop it.
Letting a Camo leak in BTD4 makes you lose 9 lives instead of 11, meaning letting the Camo's children out is actually more dangerous than letting the Camo out itself, which leaking the Camo's children cost you 10 lives.
In BTD5, Camo Bloons can be very dangerous, especially on Round 78, which contains a dense amount of Camo Ceramic Bloons.
In BTD4, upgrades of towers that help their own Camo-detection can also make other towers around those radii to be granted ability to see Camo Bloons, but this is no longer the case with any tower except Monkey Village and Monkey Buccaneer with a Tier 3 Pirate Cove in BTD5 and Bloons Monkey City.
In Bloons Monkey City, Camo Bloons can appear in assaults as well as tiles with the maximum bloon type Rainbow Bloon or stronger.