I now have five tangs in my 5x2x2 and they are fat, disease free and largely conflict free. I have a Yellow Eye Kole, Tomini, White Cheek, Yellow and a Hippo. I also have a Copperband Butterfly that is doing well. I've noticed over time the hierarchy changes but largely without violence or injury.
I took the advice in this thread and the things that worked for me are -
1. Avoiding tangs of the same genus. With the exception of the two Bristletooth tangs each is from a different genus. I don't think that body shape is really the issue, but competing for the same resources is. In fact, if you're not sure, the mouth is a really good indicator of risk. Really, hear me out! Tangs' main source of food is algae, but each species tends to prefer a different type and have evolved with a mouth to deal with that. Hippo's have kind of a toothy beak for grabbing and ripping, bristletooths scrape and Zebrasoma pick at hard to reach places. Use the mouth as a guide to whether they might compete with each other for resources.
I added the Tomini last which was risk as I already had a Kole. But at that point any aggression was spread out amongst 4 other fish and he avoids attention because of his size. Also, film and short algae which Bristletooths seem to prefer is almost always available in my tank so there's no sense of limited resources.
2. Acclimation boxes work. The biggest danger for a new tang is that it is bullied out of competing for resources. It's ok to get swiped occasionally but when it gets so bad that they can't get their fair share of food because they are too scared or weak then the problem snowballs in to infections because of injuries and starvation. I have found almost without exception that tangs will try to bully a new addition but that if injury and the grudges that arise from injury can be avoided for the first 24 hours, there's a good chance things will settle down. The acclimation box is perfect for this. All the tangs already in the tank will likely try to bully the new tang in the acclimation box. Some persistently. But they almost always lose interest over time. If they don't you can rethink the new addition. Once interest is lost you can release the new fish who has avoided any serious injury or hurt feelings and will already be wary of aggressive tank mates and will avoid them.
3. Loads of good food. Vitamin soaked meaty foods preferably home made from the fishmonger and lots of nori. Competition for food is never good and will increase aggression. The right foods can ensure health and help the fish fight off infections and heal from injuries if there have been fights. A sick or weak fish will get picked on so this is critical. In addition to loads of Nori I make a mix of scallops with roe, fish roe, shrimp, oily fish and clams mixed with some Aquaforest Vitality.
4. Quarantine and treat sick fish before adding them to the main tank. Tangs will attack weak or sick tangs. Before I put them in the DT I want them to be healthy, disease free and have enough fat stored to survive any initial stress and slow eating because of that stress. I want them strong enough to escape attack and so that if they do get injured they are capable of recovery.
5. I feel like have 1 or 4+ tangs is much more peaceful than 2 or 3. 2 tangs seem to focus on each other, 3 means that there are two to bully a more peaceful or small fish. At about 4 you start to see any aggression pretty evenly distributed and not focused on one individual.
Things I don't do or haven't done -
- I did not buy multiple tangs and add them at the same time. This probably works well but not really an option for me. Tangs are expensive in Australia so one at a time is easier for me. Also, I tend to find quarantining and treating more than one fish at a time is problematic and time consuming.
- I feel like methods like moving the rocks around and using a mirror are reactive rather than proactive and may or may not work. You are better off preventing the problem at the point of introduction with an acclimation box. It's injury and grudges that will kill the fish and avoiding those in the first place is the key. I also think that in themselves these methods are a bit dubious. Most fish will stare and taunt themselves in their own reflection when they get added to a tank and then they get over it meaning that as a distraction it has a limited effect. Also, tangs constantly roam long distances in the wild grazing and I don't think there's any merit to rearranging 'territories' in a 4 ft tank. It's not the space in my opinion, that they are competing for. It's food.
