Figure 8 vs Knight Goby/Battle of the Ages

[kaylor]

Hey There

This is my first post, I'm new here. Hopefully someone has had a similar experience and can give me a resolution. This might be a bit long.

I've got a 30 gal. brackish tank SG 1.008 (couple caves, moderate/heavily planted, argonite substrate) with 1 Fig 8, 3 Sailfin Mollies, 2 Chromdies and 2 Knight Gobies. The tank has remained healthy with very few problems since every last fish was added...about 8 months now.

As you know puffers like to nip fins. For the most part my Fig 8 leaves alone the Mollies and Chromides, occasionally I'll see a torn fin on one of them. But wow...the 2 poor Gobies have not had their full fins since I introduced the puffer last to the tank as a baby; the puff is relentless. The worst looking one is my big Goby at 4.5 inches; always looks torn up. Puff just follows him around at the bottom of the tank and nips all the time. The Goby does nothing to fight back. He's the opposite at feeding time he is the most agressive Goby...3-4 Ghost Shrimp, whole algae waffers, brine shimp clumps he even sucks down small snails, you name it he gorges on it; much like my puffer. Well my puff has been acting shy lately so I decided to play nice and dabble a store bought shrimp at the top of the tank. Mollies/Chromides checked it out with little interest...then Puff swims right up and latches onto the shrimp; he begins eating. Next thing I know the big torn-up Goby slowly swims up mid-tank and stares at whats going on, he kind wades for a second, just sort of watches and then bam! The Goby actualy hits the side of the Puffer and takes him in his mouth (puffer cannot move), shakes him violently against the glass for about 2 seconds and then spits him out. I had never heard of Gobies being agressive towards anything but other Gobies up until now.

Now here's the strange thing. After the "smoke clears" Both the Goby and the Puffer have swam to opposite ends of the tank...neither one going back to the shrimp at first. Then about a minute later Puff returns to gobble up the shrimp...but the goby never goes back. If it was a food dispute I'd say the Goby won and would have gone back for his prize. I think these two fish just don't like each other.

Anyone have a similar problem? What should I do?

My first thoughts...get more rocks, caves for the Goby to stop the puff from nipping. Goby might back off as well.

Get rid of the Puffer or get rid of the Goby, back to my LFS. I know them well enough.

Get the Puffer his own 10-15 gallon tank in my office.

I'm just not sure what to do...I really like the setup I have in the tank right now.

[Agnate]

Wow, that's intense! I honestly just think they don't like each other.

My two Ceylons never had an issue with my Knight Goby. All three of them lived in the same cave and none never had missing fins or damage of any sort.

If the Goby isn't showing aggression towards any of the other fish, I'd put the puffer in it's own 15 gallon tank. Less space, but also less stress for all of your fish in general. ^_^

[CoreyK]

My female knight goby is and has always been somewhat aggressive towards my figure 8's, much more so than them towards her. I'd definitely label a knight goby as an aggressive fish.
The puffers really have no sense of territory, whereas she does, and when they wander into it she lets them know it.
She will occasionally nip them at feeding time, and I see little puffer bite marks on her fins occasionally, but nothing serious.

The knight goby is considerable larger than the Figure 8's but I'm sure if they decided they'd had enough of her they could bully her to death, whereas I doubt she could do much damage to a puffer.

[smudger72]

When my tank was running nicely , my gobies would spawn every month on the dot.
When the male was guarding the eggs nothing was allowed near. It was amazing to see a KG literally headbut a F8 away.

[Agnate]

Hmm, maybe it's possible that yours are spawning?

[kaylor]

Thanks for the responses so far. I'd have to check on the whole spawning thing...I'm not sure on the sex of my two gobies. The big one is huge at 4 1/2 inches for a KG...the other is only about 3 inches...is the male bigger? I'd have to research this a bit more.

I do plan on adding a bit more cover to the Goby's corner of the tank. I have 2 other caves but this dolt marked the most open corner in the back of the tank as his terriorty. Maybe that'll keep Puff from nipping him.

Its been a few days and they haven't really been bothering each other; at least no more fin damage to the Goby and the Goby hasn't gone after puff during feeding. So I'll have to keep an eye on them and see how it goes. If it does continue I think I'd have to move puff to the smaller 10 gallon tank in my office by himself. I really don't want to get rid of my little trouble maker. Besides my girlfriend and her friends love to see him everytime they come by my place; they treat him like a puppy or something.

Anyone that has another suggestion just let me know.

[coldmachineUK]

I have three knight gobies with a pair of F8s in my 53G brackish tank, and they've been cohabiting for months and months now without any problems. But, the thing with puffers - of most species, including F8s - is that it's personality-dependent whether they're going to tolerate tankmates or not. There's no blanket rule. Some species are easier going than others (F8s are easier going, in general, than GSPs, say), but it's still not a hard and fast rule. You may have a meanie in your midst.

Knight gobies can be feisty too: mine occasionally bicker among themselves, though they leave everything else alone. My advice would be to add more decor/hiding spots and break up the line of sight at first. If that still doesn't resolve the problem you may have to separate your puffer as Paul (Agnate) says.

[kaylor]

Machine you're lucky that everyone gets along. Its just strange...my Puff is just relentless at nipping my big Goby. He really doesn't bother anyone else in the tank accept for the occasional nip. Been about a month since I first posted this and things calmed down for a while...the Goby's blue fin almost fully grew back. And no more battles over food. But a few days ago Puff bit it off again. The Goby lays on top off the largest rock in the tank minding his own business...and Puff sneaks up behind him and bites. I watch him and when he does it I point and shake my finger at him...he darts away. After doing this a few times now when I come up to the tank he's more scared of me, so I know puffers learns...but not what I want him to; to stop bothering the Goby. Yesterday I added a couple more silk plants...no more caves as I'm running out of room at this point. Lets hope this does the trick.

If anything changes I'll post about it.

[Agnate]

Yeah, it's quite possible that they just don't like each other.

[mike_freegan]

Removed

[Dsmdan95]

Let's see a photo of your tank. See how much cover you got?

[goby1kenobi]

Knight gobies are bloody difficult to sex, but it can be done.

The male has a very slight occipital hump that develops when he's got a female. It's really only noticable when the two genders are next to each other. The female's head will slope more than the male's head.

The male will also change colors, darkening in a display for the female.

The male tends the eggs (and promptly eats the fry when they hatch).

The male may also have a longer second spine on the dorsal fin. This is not a reliable indicator, since the spine length varies -- especially when puffers love to nip that fin!