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Odessa bully

QueenBee

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(Hopefully this is the right place to post? It's my 2nd post here)

I'm fairly new to tropical fish, have learnt a lot in the past 3 months since first tank cycled, some of it by trial and error!

I have 6 odessa in my 37L tank, I started with 4, they've been in the tank for 3 weeks. I added 2 more a few days ago. 2 males and 4 females, all around 2cm, still growing. Im aware they will need more space, I am moving them to a much bigger tank in the coming weeks, once I've purchased it and cycled it.

Yesterday, since I moved the ornaments around, one of the males has been relentlessly chasing the others. He seems to be guarding the castle ornament, rushing at the others when they come by, before swimming fast back to his castle, only to do the same thing seconds later. For hours at a time. The other fish aren't hiding from him, all of them are eating, and appear otherwise well.

His colours have deepened in the past week. He's been in the tank for 3 weeks. The other male, although marginally bigger, is still relatively pale in comparison.

I'm wondering if this is mating behaviour?

Or do I need to add a couple more because 6 is too few on the school for them?

I tested the water parameters yesterday, all were normal (zero ammonia and nitrates, very small amount of nitrates)

I'll try moving the ornaments around again in the meantime.
 

seangee

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Ideally you want more than 6 but I would not add anything until you can provide a bigger home.

These fish have a fairly complex social structure. It could just be 2 males vying for the attention of the females, but they are most likely trying to etsablish their hierarchy or pecking order. This is likely to happen every time you add fish or re-arrange the furniture and should be harmless.

I have a dozen dwarf chain loach (very hierarchical social fish) and I only need to trim a plant to kick off another round of squabbling about who is the boss. The pecking order is firmly established so this usually only lasts a couple of hours - but it used to be several days o_O
 

Retired Viking

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Ideally you want more than 6 but I would not add anything until you can provide a bigger home.

These fish have a fairly complex social structure. It could just be 2 males vying for the attention of the females, but they are most likely trying to etsablish their hierarchy or pecking order. This is likely to happen every time you add fish or re-arrange the furniture and should be harmless.

I have a dozen dwarf chain loach (very hierarchical social fish) and I only need to trim a plant to kick off another round of squabbling about who is the boss. The pecking order is firmly established so this usually only lasts a couple of hours - but it used to be several days o_O
Talk about a family feud :D and I use to think my cichlid were bad moving the furniture around every day :fish:
 

Russjw

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The limited space here will be contributing to your problem. Soon as you move them to a bigger tank this should settle down. Id then add to your group. As your aware 37ltrs is way to small for Odessa's, i have 9 in a 220 and get no aggression at all.
 

Byron

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There are a couple of issues here, and the intended course of action may not resolve either.

First issue is the number of fish in the group (shoal)...right from the beginning it should be the intended final group. With this species that means no fewer than six but a couple more than this would be preferable and less likely of future problems involving aggressiveness.

Second issue is obviously the tank space...37 liters (10 gallons) is not going to work for more than a couple weeks. I understand you intend a larger tank, but is this likely to come about within a month? Any longer and again there will be trouble.

The factor behind both of the above has to do with the fish being together. When shoaling fish are moved into a new environment, they tend to settle fairly quickly as that group. Adding more several weeks later is not always advisable, depending upon the species. The hierarchy that establishes early with the fish in the present group and tank can become isolated, which means you cannot later add more of the species without serious consequences. The stress the fish are having early on continues and may not always be reversible. In fact, I doubt it is ever reversible, it is more likely that some species/groups may develop differently than others and it depends upon the individuals and the species. Naturally hierarchial or aggressive species will tend to establish these traits early on and not be able to alter this in the future.
 
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QueenBee

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Because my tank was newly cycled, I was advised / read fish articles that said to introduce fish slowly, i.e. only a few at a time so as not to overland the system too soon (that's why I added 4 just initially).

The new tank will take a couple or more weeks to cycle, so between 2-4 weeks all going well.

Then of course, I'll have the problem of needing to add more to the shoal to reduce stress, OR keep the number as it is, least rhe y don't welcome newer fish. Although, if they all go into a new tank at, the same time, it's less of an issue?



I changed the ornaments, swapped out the castle for something that has more openings in it, and this seems to have helped - the rushing at other fish has stopped for now at least.

Interestingly, the or her male's colours have become really bright in just the last couple of hours - are male odessa's colouring influenced by stress? Or breeding status?
 

Byron

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Because my tank was newly cycled, I was advised / read fish articles that said to introduce fish slowly, i.e. only a few at a time so as not to overland the system too soon (that's why I added 4 just initially).
There is validity in this common advice, but often it can do more harm than good. It depends upon the tank, and the fish species. The larger the tank the less chance of any "cycling" issue adding a group of fish. Smaller tanks obviously have more risk. Live plants help, in fact with some fast growing plants especially floating plants, you could add all the fish you want in one day and you would absolutely never have issues from ammonia/nitrite. Shoaling fish that have aggressive tendencies must have all of the intended group added together. The larger tank will provide this--leading to your next question:

Then of course, I'll have the problem of needing to add more to the shoal to reduce stress, OR keep the number as it is, least rhe y don't welcome newer fish. Although, if they all go into a new tank at, the same time, it's less of an issue?
Acquire the additional Odessa Barbs when the new tank is ready, and then add the new fish with the existing fish to the new tank together. The change of environment for the existing group can sometimes throw the fish into confusion and they may welcome the newcomers and all settle nicely together. It doesn't always work, depending upon species, but this is not an especially aggressive barb so you should be OK. Just make sure all of them go into the new tank together at the same time.

Interestingly, the or her male's colours have become really bright in just the last couple of hours - are male odessa's colouring influenced by stress? Or breeding status?
Fish colouration can be affected (positively or negatively depending) by stress which can come from so many things; by interactive behaviours including display, challenge, aggression and spawning; by the light being too bright; by the substrate being too dark or too light; by inadequate cover or aquascape; by genetics.
 
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QueenBee

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His colour (and black fin markings) was darker yesterday morning, then faded the rest of yesterday,, and is back to being brighter this morning. I'm thinking stress, as colour change happened with changing ornaments / the other male bullying the others.
 

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