The Battle of Two Acros

The Battle of Two Acros

The Battle of Two Acros

What happens when two acros of different species start to grow into each other? Most reefers would trim them back to avoid conflict, while some just let nature take its course. The latter seems to be less common, and we are here to document just that - what happens when two acros touch and compete for space like they would in the wild. Join us along for the ride as we find out together the outcome of this conflict.


Let's meet out first contestant, an Acropora insignis, commonly known as POTO Side Chick. It's a tabling acro with fuzzy polyp extension and is regarded as a fast grower. It's been captive-grown for 5 years.

POTO Side Chick colony in POTO's 210-gallon display

On the other side of the ring is an Acropora millipora, commonly known as the POTO Chick Magnet milli. It's a good match because it grows just as fast as Side Chick, if not faster. It's been captive-grown for almost 2 years.

POTO Chick Magnet milli colony

1/07/2021 (First Documentation)

POTO Chick Magnet Milli, left, and POTO Side Chick, right, getting ready to duel. It looks like Chick Magnet is the aggressor as it guns straight to Side Chick, who is trying to grow away to avoid conflict.



Chick Magnet milli continues with the assault but Side Chick took a surprise turn to avoid contact. A direct contact seems to have been averted. No blood shed so far but we shall see.


Another look from another angle at the imminent conflict:



Chick Magnet milli drew first blood on Side Chick. Tissue necrosis is seen on Side Chick's under-branch. It seems that the milli's growth revolves around gunning for Side Chick, as if it knew and could smell its neighbor.


The aggressor is seen coming in from the right. Tissue necrosis is seen on one of Side Chick's branches where contact is made.



Side Chick has grown back over the stung area. Both sides have growth tips that have started to darken, indicating a higher concentration of zooxanthellae. Could it be a defense mechanism to counter chemical attacks and/or strengthen the tissue to better handle tissue necrosis? It remains to be seen if this will end up in an all-out bloodbath or coexistence.



Side Chick is trying to mount a comeback while taking the bulk of the damage so far by further darkening. It has also begun to grow a perimeter around the tip of Chick Magnet milli despite some fresh tissue necrosis.



Side Chick has proven itself to never be counted out. It has grown over the dead part and even seems to take on the offensive. One thing to notice also is the lack of polyps around the contact points for both acros. At this point it appears to be less about killing each other than simply trying to out-grow the other.



Side Chick has started to show growth in other places and prove to be difficult to photograph the conflict due to shading. We made some frags to get a better picture of the situation. What is revealed to us is what looks like an arm-wrestling match between the two fighting for space. Another interesting development is that Chick Magnet milli (right) has called for reinforcement in the form of a second branch!




This whole time, Side Chick has always been on the defense while getting stung and undergoing tissue necrosis. Chick Magnet milli never showed signs of damage. That is until now. The tide has turned in Side Chick's favor. Chick Magnet's reinforcement in the form of a second branch has arrived. The first branch that made the initial contact has been overwhelmed by Side Chick's growth spurt and died. The second branch fuses with the dead part and we are in for round 2. Anything is possible now.



We will try to update this as often as it is meaningfully possible, as it's a conflict that happens in slow mode. But do check back for updates.

Finally, if you are looking to add these two acros to your tank, check out our WYSIWYG section or weekly auction as they do make frequent appearances in them.