Those crazy demasonis

[elusive_fish]

I've had a colony of 14 dems for almost 2 months now, and there is never a dull moment with these guys. I have a few observations and questions to ask and thought others might be able to share some of their experiences with these fish.

Even with a group size of 14 (originally 15, one died pretty early) and a fair bit of rock in the tank, these guys sure take a toll on each other. There are some pretty beaten up looking fish in the tank, but somehow they keep on keepin' on. One of them got his tail almost entirely removed and his dorsal fin had a chunk out of it. In my experience, most fish in this condition would stop eating, start sulking and get sick/further abused and die (without intervention that is). But this guy still fed, still tried to chase others and eventually grew his stumpy tail back. Another had his gill flap practically pulled off, but it still seems to be eating and joining in the mayhem. I'm amazed.

I guess these guys start breeding pretty young and small! I'm positive a couple of them are holding at the moment, despite them only being about 3-3.5cm long. Could this be right? The poor females really take a beating, I hope they can put up with it so I dont end up with a tank of just angry males.

All the agression does seem to be towards conspecifics. They dont even seem to notice their tank mates.

Another question I have is around the barring on the fish. A couple of them have dark blue bars that 'fork' part way down. Is this normal for dems?

[phoenix44]

I bought 25 I think as my first and only colony. Would love to get a massive colony in the future.

They are agro towards each other, and I think I had 4 very dominant distinctive males in the tank that didn't normally venture into another males territory. You definitely need a LOT of hiding spots with these guys. Breeding them is dead easy too. just get a colony and let them go nuts.

best not to buy tiny ones too, I bought all of mine at like 3-4cm and they grow relatively fast. that is the smallest size i would buy them at, but having said that you probably don't want to add large males into another colony either.

[ryanjury]

Yeah you need a good number to start off with to spread the aggression sounds like you started off that way which is good, it is also possible you have heaps of males so if things don't settle down then you might need to thin a few out and see how that works out for you. How big is the tank? My colony is at 25 at the moment too with around 10 smaller ones I added to grow up in there and increase numbers, I have had to thin out males a few times and will have to do so again when the smaller ones grow up and start causing trouble. I think you may be at a stage where this is something you should look into if your fish are getting damaged and a real hard time. Their aggression is pretty much only directed at their own kind which is something that I find not alot of people understand, lots of people won't touch them as they think they will destroy all their fish.. I have long finned rosy barbs and swordtails happy as in with my colony/peacocks/yellows.

I also have an exception that goes against all the rules (and what I would ever recommend) with my dems in that I have 3 adult males in the same mixed african tank with no damage to any of them only one is fully coloured and obviously dominant but the other 2 are healthy and happy with perfect fins etc.

The random barring is normal, I don't keep or breed the fish that have this but it is normal just depends if you like it or not it is not an indication of hybrids or anything it happens in the lake..

Have to disagree with Phoenix I find it better to get the fish smaller and grow them out together so they sort themselves out and grow up together as a colony. As always with a colony forming fish a colony that has grown up from small together will get along better and have more chance of long term success. You will also have more success adding younger fish to your colony if you add them small (and in groups) as they are seen as less of a threat to the bigger fish and can fit into smaller holes so are pretty much left alone. Dem babies are also hardy as, I got my first batch of 65 (5 or so years ago) all of them stripped straight out of their mothers mouth into a bag took them home and raised them with no issues.

Breeding is pretty easy just add heaps of rocks and stuff and babies should survive they are pretty tough, and yeah they do start breeding really small but broods are small initially, you can also catch and strip the fish but I find them exceptionally hard to strip and have killed a female or 2 trying to do this so it is not ideal.

[elusive_fish]

Here are a few pics of my tank as it currently looks.

I've tried to provide plenty of rocks. Pretty boring to those with lush aquatic planted tanks!

A couple of my dems

One of the holding dems. You can see how big she is in comparison to the heater.

Others in the tank:

Mr Syno wants to be photographed

My male brown hap

One of my male peacocks

My big ice blue male really doesn't like the camera much, he's hard to get a photo of.

[ryanjury]

Nice fish

One thing I have found with territorial fish is to make clear territories the way you have it it is very easy for a male to lay claim to a large area as it isn't very well broken up. I have also found if a fish does get a hard time it tends to try and find shelter higher in the tank, in your tank these fish going higher have nowhere to go so maybe trying to build a higher stack would be better for the fish that are getting a hard time?

[elusive_fish]

So would it be better to replace the rock 'wall' with, say, 5 smaller piles of rocks?

[ryanjury]

I would try smaller piles and see how that goes for them, try and stack them up higher (obviously being aware of their stability) in the corners to give bullied fish somewhere to hide..

[spoon]

ive got some slate you can have for free if you want it

[elusive_fish]

Man keeping fish can be frustrating.

The two holding dems are looking desperately thin. After tearing up the entire tank last night I caught the one pictured above and put it in breeding net stuck on the side of the main tank. She didnt settle and was going a little ballistic trying to get out, so i decided to try and strip her. Man, Its NOT easy to strip a 3cm fish! I managed to get it to spit a couple of young, of about 4-5mm length before I felt like I was going to stress her to death. At that point i left her in the net, turned the light off and went to bed.

When i woke up this morning the net suckers had let go, the holding female and babies gone and a bristlenose and male dem hanging around in the net instead. Then I managed to kneel down on the glass lid and break it.

So now there are still two small holding dems in the tank, looking quite skinny and worse-for-wear. Will they spit soon or is it possible they will hang on so long they will get killed?

If I should catch and strip them, any tips on doing it with such small fish? I dont even know what to do with the babies, i really dont have anywhere to set up grow-out tank and the damn breeding net doesnt seem to want to hold on with the suckers provided.

[ryanjury]

TBH dems are pretty hard to strip, I have killed a female doing so and it is very stressful on them, it just gets harder as the fry get more developed too as they start swimming back into the mothers mouth.

Generally the females will spit when they are ready just provide lots of hiding places for the females to chill out in and for babies to survive in after they are spat. Usually removing dems to spit themselves is a bad idea as introducing them back into the colony can be an issue.

Breeding nets aren't very good as the fish in the tank try and eat the babies through the netting this ends up getting them sucked into the netting and killed anyway, the plastic guppy traps can be ok as they have less holes for the fish to try and suck the babies through.

Have you considered thinning out males to make things easier on the girls?