Figure 8s Fighting

[wetmartini]

A few days ago I purchased 2 F8s for a spare 20 gallon that I set up with a few rocks and plants (3 red mangroves and some anubias nana). Tank was cycled last week with media from my GSP tank’s filter (SG 1.10). The F8 tank currently has the following parameters:

pH: 7.8
SG: 1.005 (measured using refractometer)
NH3: 0
NO2: 0
NO3: 0

Generally, the puffers are healthy and are doing fine aside from having some very torn up fins from their stay at the LFS. Color has also improved dramatically.

The only problem I have is that these guys just don’t seem to get along. I thought (perhaps mistakenly) that F8s did fairly OK in a conspecific tank, but these two frequently harass one another, even when I am not feeding them. Sometimes they circle around one another like a pair of boxers. From a certain perspective it is kind of amusing to watch - I’ve never seen fish behave like this. But for the sake of their long term health, I’d much rather they get along.

Granted, the tank is pretty bare right now - I had planned to do some extensive aquascaping by adding several large and small rocks and many more anubias, but just haven’t had the time to do it yet.

Does anyone know if this situation will improve over time (they were in pretty rough shape at the LFS - 20 or 30 of them together in what appeared to be a 30 gallon tank) or with the addition of more decor to break lines-of-sight? Or, will I have to bite the bullet and return one to the LFS?

[RTR]

It is highly unlikely that the situation will improve. A 20 is far too small for two highly active and territorial hunter-predators unless they have been co-housed since they were tiny, and is still too small for their permanent home even in that case. I do not co-house these fish in less than a 4-foot tank anymore. A 33XL will do, or they wiould love a 40-long - IF they were compatable, which this pairing may well never be. These are highly active and strongly territorial hunter-predators. You may not ever be able to co-house 2 adult males. If I see disputes, I put in a divider immediately and/or re-home one or the other immediately. Otherwise they may outright kill the weaker fish or permanently damage it's fins. When these particulat fish show incompatability, I do believe them. The do seem to enjoy seeing conspecifics in adjacent tanks, but not often for me in the same tank unless co-housed from early youth, and not always then.

Your pH is excellent. Do you know the KH?

I distrust 0 nitrate readings. Is this by liquid-based test kit?

HTH

[wetmartini]

Thanks for the reply RTR. I figured as much. I have already separated them and put one into a large tub - I plan to return him to the store tomorrow. I am using a mixture of aragonite sand and natural gravel for the substrate. Red Sea Marine Salt was added to achieve the proper salinity. I have been checking water parameters almost every day for the past week since this is a new tank and the last thing I want to do is have my F8s die only to wait another 6 months for them to show up in Korea. The readings have been pretty much the same every day with the exception of a small ammonia spike the first day or two. I will test water again tomorrow and see if there is any reading for nitrate. The parameters I posted were from yesterday but that was before I did a 50% water change.

[JRC3]

A few days ago I purchased 2 F8s for a spare 20 gallon that I set up with a few rocks and plants (3 red mangroves and some anubias nana). Tank was cycled last week with media from my GSP tank’s filter (SG 1.10). The F8 tank currently has the following parameters:


SG: 1.005 (measured using refractometer)

I would also think a change in SG that drastic would kill off the bacteria in the media. Keep an eye on the params.