I have my idea on who the culprit is.  Whoever it was, they are lucky I didn't see it happen!  I want to get another Arowana, as they have been one of my favorite fish for the past 10 years, however I recently set up a new tank and have put fish in it I have no experience with..so I'm not really sure which ones are fin nippers yet.

Some info.

The tank is a 135 gallon all glass, set up about a month and a half ago.  Rock substrate, 2 36" fake plants, and 2 24" fake plants, driftwood and small caves litter the bottom.  The tank looks really nice, and all the fish in it seem happy and comfortable.  There is plenty of places for any of the fish to hide.  I also have 2 breeder nets in the tank, one with feeder guppies, and the other with a couple electric blue jack dempseys, Flower Horn, and irridescent shark, that are too small to mix with my other fish.

Now for the fish. These ones I do not believe were the culprits.

Red Tiger Oscar 5" (will eat anything it seems)

Jack Dempsey x2 3"

Electric Blue Jack Dempsey x2 (small and in a breeder net)

Flower Horn (small and in a breeder net) 

Tiger Shovel-nose Catfish 6"  (hand feed him, because with all the voracious feeders in my tank, its hard for them to eat, since guppies disappear so fast after I drop them in)

Red-tail Catfish 6" (just started hand feeding him, really cool watching)..tried to feed them at night with guppies, but my other fish still ate al the guppies before the catfish even knew they were in there.

Clown Knife (could have possibly been him, but he shows absolutely no agression towards any fish, aside from guppies) 6", eats pellets and live/frozen food

Black Convicts x2 3"

Clown Loach x2  2-3"

Large Pleco 8"

Dragon Goby (i think thats what its called...wierd fish, I dont really like him) 6"

Irridescent Shark (small and in a breeder net)

The following are the fish that I think did it....these are also the fish that I have never had before, so I didn't know much about them

King Kong Super Red Parrot Fish (the arowanas back end had a chunk missing in the shape of a triangle, and his mouth is triangle shaped, however I dont really see how he could have done this, as his mouth seems so oddly shaped.)  Ive never had a Parrot Fish, so I dont know if they are fin nippers, or even if they can nip fins, due to their mouth.  Fairly Large 5-6"

Red Pacu  Fairly large  5-6" (I think the pacu did it...he is large, eats a ton, and a few days before this happened, he discovered that he has a taste for guppies...he seemed to accidentally inhale a guppy....after that, all hell broke loose, it was almost like the guppy was crack to him, now he destroys guppies as soon as i drop them in)  My father, who has always had fish thought it was the Pacu, as well as the local fish store. 

I just want to make sure I get the correct fish out, before I buy another Arowana.  The Arowana was only about 4" long, so next time I will buy a larger one.  Right now I am thinking of putting the Pacu and the Parrot Fish in my 55 gallon tank, however i like both of them, so I would rather keep them in my main display tank, but not if they are going to be killing my Arowana.   I realize any fish COULD have done the damage, and could possibly bite any fish, however if Pacu's have a history of doing this kind of thing, that would be good to know.

So who do you guys think is the culprit? 

Thanks for looking!

Rob

How long did you have the arrowana before this happened?

Realistically any of the fish, except the ones in the breeder nets and probably the clown loaches, pleco and dragon goby, could have done it (although I would probably also put the clown knife on the didn't do it list).

Cichlids and other similiarly aggressive fish can get worked up at times and really start flying off the handle.  It is even possible the arrowana got spooked, knocked himself out by hitting the glass and then the fish started picking at him.  Without seeing it happen, I am not sure if you will truely know what happened or who did it.

Hopefully you don't mind a few comments on the fish in your tank.  5-6" is actually fairly small for a pacu.  They can get in excess of 24", so be ready for a big fish.  Same with the red tail catfish...be ready for a huge fish (I think they can get up to 5 feet, you will need a bigger tank).  I would also consider taking the irridescent shark out, they generally do not do well in aggressive tanks IME.

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Keith

"Simply put, you believe that things or people make you unhappy, but this is not accurate. You make yourself unhappy." Wayne Dyer

We should also consider the possibility that the fish was ill, stressed or unable to properly defend itself due to environmental or other factors. I think any fish in such a tank that falls ill will be picked on and chewed up... kind of like finding a fish stuck to an intake and blaming the intake for killing the fish...

Good luck

Giancarlo

Giancarlo Podio

I dont mind comments at all, thats why im here!  Often times people will point out stuff I have never thought of, so having more aspects helps out alot in this hobby.  However, let me explain my situation here, and you can understand a little more my thinking.

I have had the Arowana for about 3 weeks now.  Since setting up the tank, I have not had a fish die aside from being eaten.  All the tests have been good, after the initial cycling period.  I have a little over 10 years experience in this hobby (off and on), so I at least know the basics for freshwater.  No medication has been used in the tank.  Do weekly 15% water changes, taking and adding water into the sump, so I dont disturb my fish.  They all seem healthy and happy.  All the fish eat readily, and I usually hand feed the catfish (by hand, i mean with a grabber), so they get a chance to eat.  The arowana ate just fine as well, so nothing to assume he was ill or stressed.  He cruised the top of the tank like the Arowana I had 10 years ago.  The only major change I did in the water was I put some Catapa leaves (im sure thats spelled wrong) in there about 2 days before this happened. 

I only have the Iridescent shark in there, because I am currently in the process of buying a house, so it didn't make sense to set up a whole new tank for him and the smaller fish just yet, just to take it down in a couple weeks.  But for the time being, just putting him in a breeder net seemed like a good idea. 

I also know these fish get big =), thats why I chose them!  When I put in my original post that the Pacu was fairly large, I only meant in relation to the average fish in my tank.  I have kept all these fish before, except for the Pacu and parrot fish. I did see a 9 year old Pacu at a LFS and he was massive...just wait til I get my Arapaima! 

The 135 isn't a permanent home, but for a dozen and a half 5" and smaller fish it seems plenty big right now (I also have a 60 gallon new sump, for close to 200 gallons of water.  My 210 gallon tank is also not set up....but again, realistically setting up a 210 gallon or larger to stick a few 5" fish in is a little overkill and didn't seem smart with me moving soon.  I also had planned on turning the 210 into a reef tank (This is where I dont know much...salt water setups!  Could really use help there). 

 The basement in the house I am buying is extremely large and open, and I already have plans on having an extremely large custom built tank in there at some point, probably at least 2 that are a few thousand gallons. 

Im definetely not one of those people who just goes into a pet store and buys cool looking fish I see wthout knowing about them.  I generally research every little thing I do and would never buy a fish I could not take care of when its all grown up......Just look at my Light post in the salt water beginners section...I did research on lights for like 2 months before I asked for more opinions.

All that said, I would like to get another Arowana in that tank..but I cant prove what fish did it....I just dont want it to happen again.  I will just have to keep my eyes open for a bigger sized one.

Thank you for your comments, and thanks for reading again!

Rob

Thanks for the background and upcoming plans.  Sounds like you have some incredible work ahead of you.  When you get the basement tanks set up, please share some pictures. 

Keep us updated and hopefully you find that arowana you are looking for.

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Keith

"Simply put, you believe that things or people make you unhappy, but this is not accurate. You make yourself unhappy." Wayne Dyer

When I do tackle that project, I plan on taking lots of pictures, so I can definitely post pictures of it.  Luckily I have quite a bit of supportive people around me to help out, and I love keeping busy doing busy work. 

Me, my brother in law, and my father have been interested in opening a pet store in the area at some point, that specializes in Fish and reptiles.  My father breeds snakes and lizards and builds incubators for a living, so he has all the knowledge for the reptile side of it .  Him and my mom run the business right now, His site is www.Nsreptiles.com .  He has some nice pictures up there of his animals.  When I started to get into fish again, his interest started up again as well.  He is a big DIY guy, so he helps me out with most of my projects I tackle.  So this is a hobby that I can enjoy with my dad and my brother in law....what more can u ask for!?