Orandas Wen being eaten?

Question
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Followup To
Question -
I have 6 Orandas 2 black moores, 1 angel Fish, 5 Ryukins, 2 Otos, 2 Black ghost knife fish and 1 fantail. Ok Basically a few days ago i noticed one of my orandas head half eaten away, and another with blood spots on its wen and i got worried so i just sat near my tank and just watched all the fish were fine including the ones that were injured as if nothing was wrong... so i was really confused then i noticed the black ghost knife fish swimming around playing with the other fish and just sniffing them and annoying them and going in circles and then theyd go to the otos and then the black moores etc. and they follow each others tails in circles like crazy all fun to watch until i started wondering if they were the ones eating the orandas wen. so imediatly i moved them to a smaller tank but they are misrable there and i noticed that the oranda with the blood spot on her wen seems to be eaten after i took the black ghost knife fish out? Confused... so i read on the net it could be the otos and some other place it said that the ryukins good nab at there wens at times.. i really dont know what to do... the Aquarium is crystal clean... Temp is at 25c.... there food is frozen blood worms exported from china... i really dont know what caused the eaten or rotting wen? and i want to put my depressed black ghost knife fish back to the 90 gallon tank they seem misrable all alone in a small tank.

Thanks for your time and effort.


Naz   
Answer -
Hi Naz;

The knife really shouldn't be with the goldfish at all. As you now know, the knife is more active but the goldfish are slower and can't get away from him. Knife fish also have an electrical charge that comes from their bodies and are suited for tanks with semi-aggressive and aggressive fish. He may be stressing the goldfish and actually causing physical damage, directly or indirectly. What you see as boredom in the knife could actually be just calmness from not having to chase the goldfish out of his "territory". For some reason he just doesn't like them. Otos are very rarely even remotely aggressive. I really don't think they have the capacity to cause the kind of damage you have described anyway. If they were chinese algae eaters or plecos I would say it's possible, but not the little otos.

One serious concern is that the goldfish could easily develop infections. Redness indicates bacterial infection or they could just be bleeding from the open wounds. On the other hand, redness on the wen can simply be more growth. If it is in the little valleys or creases and the fish acts fine, they are probably growing more. Make sure their water is very clean. Replace 25% of the water every week on a regular basis. You can even do it twice a week right now to really get their immune systems working better at fighting infection. Vacuum the gravel too. It is best done every 2 to 4 weeks with the water changes.

Their diet needs some changes too if they are to stay healthy. Bloodworms are okay once in awhile, but not as a daily steady diet. It just has too much protein. It's fine for the knife, but not the goldfish. Here is more on dietary requirements for goldies;

http://www.goldfishinfo.com/feeding.htm

At Your Service;
Chris Robbins

hi again

Thank you very much... sorry i was mistaken i thought the two fish i had where otos but when i looked them up you where right they are not otos there Plecos with lepord dots kinda thing... but they seem harmless anyways... about the blood spot its now a bigger hole like some ones been munching on the orandas head but the others are the same there no additional bites... However i am led to believe its the Angel fish thats been eating the wens cause i saw her biting the injured oranda in the same exact spot and keep running away and the hole is a little bigger now... plus shes been biting the other Goldfish all over i've seen her her bite there bellies there tails etc. so i basically took her out and put her in a tank on her own... if thats ok.... and i kinda felt sorry for both the "Black ghost knife fish" and put them back with the goldies yesterday... oops... but they seem like there ok?.... i read that there not as aggressive as there brown cousins?  I have been taking 25% of the water out and renewing it every 2 weeks i guess i'll change it to every week.... and thank you so much for the heads up on the feeding someone told me its better for them if they just ate the blood worms no wonder theyve been munching on the plants... " i thought they were having appetizers before there main meals" lol....  i appreciate the help.. i hope my orandas get better after i took out the Angel fish.... by the way some one told me it could be a disease called the Hole in the head or somthing were the orandas heads just rot away and then they die? i really hope its not the case with my fish cause first of all not one pet shop around this place has any kind of medication for Goldfish problems all they advise me to do is add salt... and thats all i can think of... i must say though thanks again for your time and efforts...

sincerely Naz

Answer
Hi Naz;

I did forget to tell you the angel could be a problem too. They are cichlids and can get very aggressive. I'm glad you were watching and figured that one out on your own.

Keep in mind that the knife is nocturnal so he could be picking on them at night when you don't see him. Open wounds are just natural targets for other fish, even if they aren't normally aggressive.

Make a 25% water change every other day for a week or so to get the water as fresh as you can. This will help prevent infection. Salt is actually helpful as long as it is pure salt with no additives. They can have a dose of 1 teaspoon per gallon. It helps ward off infection. If the water is clean and there is salt in there, they should heal on their own. As you make partial water changes, add only enough new salt for the new water. Don't treat the whole tank again.

Hole-In-the-Head is a disease usually found in cichlids and other larger predatory fish. It is very slow progressing and related to dirty water and bad diet. I've never seen it in goldfish though. I think they have just simply been picked on. The treatment is the the same as I described already anyway; Clean water and well-rounded diet.

At Your Service;
Chris Robbins