Add more sewellias to decrease aggression?

[shuwae]

I have 3 sewellias with 5 gastromyzons. The big sewellia is picking on the other two smaller sewellia, constantly. Should I add more sewellias to decrease aggression or am I just asking for more trouble? I don't really want to add anymore as this is a 23 gallon tank. The aggressive sewellia doesn't pick on the gastromyzons, only the other sewellias. Every time the smaller two are in the big one's sight, it always chases them until they end up at the other end of the tank, even when on the glass wall. There's enough hiding spots and this aggression issue just started about a week ago. Tankmates have been together since October and the 8 loaches are the only stock in the tank.

[mattyd]

I have 4 sewellias in a small 1ft wide by 1.5ft long space. In the tank I normally have a MASSIVE load of fist size and bigger rocks, carefully placed so that they rest on top of each other and against the glass. Sure, there isn't much straight swimming space down low, but each fish has many many hiding places and my sewellias that are in a longer tank barely swim further than 30cm in a go anyways. Now back to the small tank: There is a bright light that sits on the glass lid, 6-8 inches above the rocks. This encourages a LOT of algae growth on all the top facing rock surfaces. So my fish always have something to graze on. Most of the time I can only ever see one or two of the guys at once as they notice me and skitter away out of sight. I think with all the hiding places they are easily able to avoid each other.

The filtration I have on that tank is a very thick sponge set up in a mattenfilter style. It is about 3 inches thick and is 12 inches (30cm for us Metric folk) wide by 15 inches tall. It touches the glass lid. I have it sitting about 2 inches out from the back of the tank, and I have 2 air rises made out of bent pvc. I drilled a hole in the PVC about 2 cm from the bottom and pushed an air hose into each. The air rises pulling water with it, and the end of the pvc is bent and pushed through holes in the sponge, so the water gets deposited high in the tank above the rocks. The water is extremely aerated.

I went to clean the tank properly yesterday, intending to remove most of the mulm and debri. Obviously the debri can't get filtered out by the sponge, and because of all the rocks most of the debri doesn't get picked up in my standard water changes. I pulled out all the rocks carefully (making sure the sewellias had let go before the rock was completely removed... those guys can even skuttle around a wet rock when it is 1m above the water so that is something to be wary of!! oh, and they climb glass panels and buckets with ease if they want to try and get out - so always have a lid on the container!). With no large rocks in the tank, the only places to hide for the 4 fish was around the small pebbles, which isn't much of a hiding place. I then started stiring up the top of the gravel and sand substrate, whipping the water into a circular frenzy and lifting a LOT of loose debri and sediment into the water colum. I then go off to get my vacuum and a clean white bucket, and come back to see one of the fish chasing another fish around... I watched with interest, wondering if this was agression. But nope, not agression, because right in front of my eyes I witness a mating / spawning where the male locks his fin into the females fin and they cirlce around on a spot a few times and then let go. This happened about 3 times. Now I was too worried to do a water change... lol. He then left the little lady alone (who gathered herself together and hid behind a rock and didn't move for about 20mins. hehe). He then started chasing another, but I am going to assume that the other fish either wasn't a female, or she wasn't interest in his attentions.

So the moral of my story is maybe put in more rocks which provide all around hiding places, and maybe the agression is an amorous male trying to get a female interested.

Matt

[shuwae]

Half the tank is filled with rocks. I'll see if I can add more rocks as I don't want food or other stuff, getting stuck between the rocks. I also have driftwood in the tank, where the sewellias hang out most of the time. The sewellia hasn't been aggressive these past days so I hope it's because it wants to breed.

[Jim Powers]

I think mattyd makes some good points.
Have your tried sexing the fish to see if the ones that were being chased were female?
If this is spawning, hopefully you will get some fry.
Its interesting that your Sewellia have not been bothering the gastromyzons as many on this site have reported. I, too, keep the two species together and it seems to work out well. The Sewellia will chase the gastros away from food, but I make sure to put food in mulitple areas of the tank so everyone eats well.

[shuwae]

I believe I have 1 female and 2 males. It's just the aggressive sewellia that is chasing the other two. The other male doesn't chase the female. The alpha gastromyzon chases the aggressive sewellia even though the sewellia is bigger than the gastromyzon which I find weird as I read that the sewellia would pick on the gastromyzon. I plan to add more rocks when I get a chance to either buy or go collect them as the loaches tend to fight over one certain rock even though I have different rocks in the tank. I don't want to add too many rocks that the gastromyzons hide all the time which happened in the old 20long.

[Jim Powers]

You might set up the rocks in a manner that blocks some of the sight lines and so the aggressive sewellia won't always see the others.

[shuwae]

Thanks. I plan to redo the tank on Friday when I add the new filter as I am also cleaning some rocks to add to the tank. I hope it helps stop or at least decrease the aggression.