# Blue eye forktail rainbow aggression?



## brian3676 (Dec 21, 2014)

My tank had 2 blue eye forktail fish. Few days ago I got 4 more to grow the school since they are a schooling fish. Today I noticed that it seems someone is picking on the new ones as there fins are partially eaten. I can't figure out what, as all my fish are community with the exception of my GBR. Is it possible the 2 old forktail don't want to accept the new ones? After much Googling I can't find anyone ever talk about aggression with them. 

Other fish are:
9 Glow light danios (trying to get more but they are always out)
1 German ram
3 Otos
2 glass catfish
3 cory catfish 
3 zebra loaches
2 gold killi
1 twig catfish
8 rummy nose tetras 
2 vampire shrimp
4 frogs
5 long fin white clouds
10 blue eye forktail


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## WaterLife (Jul 1, 2015)

I keep many species of Pseudomugils (yours is Pseudomugil Furcatus) and never had them "eat" or damage each other's fins. Some might "smack" each other while chasing each sometimes, but never any damage. I did once have a overly mean/competitive threadfin rainbow and also a Gertrudae rainbow, but they would just non stop chase and display at the other male/females actually causing the other fish so much stress that they would constantly be running away. Out of all the Pseudos I kept, that were just 2 odds ones out of the bunch, but are today very calm after I did a attitude adjustment (separated them from the rest a while and reintroduced the, behavior has not been a problem since).

So now on to the cause of damaged fins, have you seen the forktails actually dong the damage? Like mentioned they can possibly chase each other, but I haven't seen damage, (potentially splayed fins, but still haven't seen that), especially "eaten" chunks. Causing split fin rays and eating fins are two completely different things, if split I could potentially see that accidently happening if they ram each other, but never heard of them nipping. But there are always exceptions and rare occurrences out there so anything is possible, so if you really do witness them ripping chunks out then that in fact may be the cause, but do keep a eye on the other suspects. I had peacock gudgeons before and they never nipped during the day, only at night when the fish were sleeping/less active, just a heads up.

From the livestock, I would say the Killifish would be my number one suspect as they can be mean. Second runner up would be glow light danios since their school is rather small which can cause unnormal stress and as a result sometimes aggression from that. The others don't ever equate to fin nippers in my experience.

Just be sure the new fish don't have fin rot.


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## Goldie (Aug 27, 2015)

I had this problem with my dwarf rainbows, missing fins and all. I took the agressor and put him in a small breeding pen for two days and then reintroduced. All is good now.


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## brian3676 (Dec 21, 2014)

So a few days ago I added to the schools. Added 6 more glowlight danios to make the group 9 total. I now have 10 blue eye forktails total. I watched them for around 2 hours yesterday and I am fairly confident that it's the 2 older blue eye forktails that are the aggressor. I watched them pick on the smaller ones. They actually even pick on the danios. 

I am wondering if it's not actually being aggressive so much as playing, and the bigger ones don't understand the smaller ones can't keep up. I know they are supposed to be very playful fish.....


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## AquaAurora (Jul 10, 2013)

I've kept white clouds with another fish and they ignored it while still juvies but once sexually mature/full grown they shredded the other fish's fins.


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## lksdrinker (Feb 12, 2014)

Wow quite the variety in that tank. How big is it? Could be worth pointing out that a lot of the fish you've got listed there want some very different water parameters. For example the ram wants to be in a tank that is around 80 degrees while your minnow and killis want to be closer to 70 degrees. This could lead to some trouble in the long run besides the aggression issue you're dealing with now.


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## brian3676 (Dec 21, 2014)

I just made an excel file of all my fish and there water temps, It seems most are happy at 75-76, which is what I keep my tank at. I just went off the recomended temp range on liveaquaria.com. 

Its in a hi tech 55 gallon tank.


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## brian3676 (Dec 21, 2014)

Since I have pulled out the 2 forktails I was suspect of doing the nipping, my fish seem much calmer and I have noticed no new fins nipped. 

I read a few placed pulling them out for 24-48 hours and then re introdicing them to the tank can sometimes help. Anyone try this? These stupid fish are crazy expensive so I hate to get rid of them....


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## WaterLife (Jul 1, 2015)

Yes, taking out aggressors and reintroducing them later can fix the aggression issue (assuming the aggression is not common amongst the species). I've done this with over-active Pseudomugil Gertrudaes and threadfin rainbows.

Not sure if 24-48 hours is long enough though. Might be, I just never tried. I've always done a week or so.


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## brian3676 (Dec 21, 2014)

I'll try keeping them out for 2 days at first. I don't really wanna set up my other tank if I don't have too. Right now I just have them in a bucket and change the water every morning since no filter.


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## WaterLife (Jul 1, 2015)

Sounds like that can. Should be enough oxygen in the water for the fish (depending how many gallons) and the toxic levels should stay low since the daily water changes for a small fish in a good amount of water.


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