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(Possibly) Adding a Six line to a stocked 14g Reef


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Hey all, this is my first post here so go easy on me 🙂


So I'm in a bit of a pickle trying to decide if I should get one final fish (Six-line wrasse) for my IM 14 gallon nano. 


The tank has already been up and running for about 4 months and it currently stocked with the following:

  • Black Ocellaris Clownfish
  • Ocellaris Clownfish
  • Blue Neon/Sharknose Goby
  • Hi-Fin Banded Goby
  • Tail Spot Blenny


I already know the popular answer is that adding a six line on top of this stocking is asking for trouble but I'm just curious if it could be possible. I've already done some research about six lines and they are reef safe and peaceful but can become aggressive if limited on hiding space. The thing is all of my gobies and my blenny stay in like 1 section of the tank the entire day and don't really move unless its feeding time (My banded is paired with a pistol so it spends most of its time in their cave). So the only real competition in the open water is the clown pair but they also host in the back corner near my wavemaker so most of the front and opposite side of the tank is mostly open to swim in. And like I said I know I have a large stock list already for a 14 gallon but as I sit here next to the tank I am not even able to see a single fish so I just feel like there would be plenty of room for a six line to swim and hide but maybe I'm wrong about that. The next thing that should be called into question is the bio load. We are told to not overstock our tanks as we might max out the bio load of our filters and live rock. I'm not sure if my filtration and weekly WC is too effective or what but I struggle to get any visible readings for nitrate and I feel like adding a six line would help dirty up my tank and help my corals with some nitrate.

Like I said previously, I know the common answer is that adding a six line to the mix wouldn't be a good idea but considering all of my inhabitant factors and my due-diligence with maintenance, could this be done without causing harm to six line or any other tank mates? Also worst case I have a 10 gallon nano waiting to be set up that I could transfer the six line to if things go bad.

Thank you for reading and any advice!



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They are not peaceful. They are territorial fish. Now there are always exceptions and small sixlines tend to be more passive side then adults. 

I just wanted to point out it isn’t because of hiding (but yes they do need/enjoy caves)… it is generally in their nature to bully other fish and drive them away from their space which is a lot larger then 14g in the wild. 

It would probably work for awhile but it’s a very real possibility that your sixline will kill another fish in a year or two. 

They generally would prefer more space then a 10g so not sure that backup plan is ideal. I would get at least a 20 long. Adding it as the first fish to a 20 though means it may attack newcomers more so. 



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You should not add an aggressive, reasonably active fish to a small tank that's already more than fully stocked. 


If you absolutely need to add another fish, try a cardinalfish. Open-water swimmers, not aggressive towards things that aren't shaped like cardinalfish.

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9 hours ago, TylerNano said:

I've already done some research about six lines and they are reef safe and peaceful

I've never heard the word peaceful and six line in the same sentence. 😆 Here is the thing you already know that it's not a smart idea to add the six line . And try catching that guy in your tank if you want it out. Ya will have to tank the whole scape out just to catch it 

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Okay so maybe my research misled me and they are not peaceful. So if a six line isn't a good idea what would you guys suggest as an alternative? An open water swimmer that wont be overly aggressive and reef safe. I'm not against a cardinal but id like to maybe get a little more color in the tank. 

My idea behind this is I rather get another open water swimmer to fill out some space and also help me increase my nitrate rather than having to dose nitrate.


Thanks for the comments so far guys!

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Would you be open to something like 1 Nemateleotris decora, or a similar small dartfish, if you want colour?


Adding to a tank with an established clownfish pair might be your only risk... Some clowns are quite peaceful, some are d1cks; and it can be quite subjective to the individual fish in question IME. 


I love igreens guide to nano fish for an easy to read starting point for stocking research though. 



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First the bio load would be quite high but if you really want another fish I would definatley look for a possum wrasse. Very sweet personality and they require little space.

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Possum or pink streak wrasse (swims close to rockwork, pinkstreak is less shy but harder to find)


Fang Blenny (generally okay with combtooths but I have seen tailspots actually get nippy at other fish so YMMV)

Firefish (hover out in water column but easily bullied).

Springer damsel (generally more laid back for damsel)


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