what causes aggression in oscars?

Neervana

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May 17, 2008
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well for the first time yesterday my tiger oscar started accepting hikari gold pellets - before he would just eat them and spit them out again. i fed him again today and i've noticed that since i started feeding him the pellets, he has become very aggressive. why is that? i feed him beefheart, shrimps, king prawns, bloodworms, spirulina pellets, and JMC protein pellets. before he started to eat the hikari gold pellets he was calm - as in swimming around all over the place but now he has tried to jump out of the tank three times (hear him hit the tank lid then go back down again) and he is starting to headbutt the wall of the tank whenever someone else comes into my room. also, he began chasing my clown loach, ornate and gold nugget so i moved them because they were all getting really scared. what should i do? just stop feeding him the pellets? i've checked all my water parameters, they are the same as usual, no ammonia etc so i don't know what else could have caused this sudden aggression. the only thing that could have caused it is the hikari pellets because that's the only new thing for him...:confused:...or is this normal for growing oscars? he's about 10 cm in length now, when i got him in may he was probably 6 cm but he's grown a bit.
 
Hmm.. I think that might be just the way oscars are. I could be wrong, probably depends on personality
 
i was kinda thinking the same thing but then he's never been like this before. sure when i first took him home he did sulk for a bit but he seemed really happy...now after feeding him pellets yesterday...he just keeps on trying to get out of the tank...maybe i will stop giving him the pellets and see what happens?
 
Hmm well... :O Strange. Whats your water quality at the moment? is it too soft? I think these guys like it alkaline hard 7.6 or 8.0 of pH. Then again I don't have experience with oscars so hopefully oscar experts chime in and help you out :)
 
no, the water is hard in london - so mine would never ever be lower than 7.6! hmmm i don't know why he's acting like this! Calling All Oscar Lovers!
 
My O' trys to jump out of his tank when he's being chased. I don't think it will be the food, it sounds like normal oscar behaviour.
Clown loaches don't make good tank mates for oscars though, they also need to be kept in a shoal of 5 or more. Clown loaches can grow to 16" and require a ver large tank with non-agressive tank mates.
 
well i've moved the clown loach out now, so shouldn't be a problem. he is in the 600L with the gold nugget and comon plec and ornate. i actually had 6 clown loaches to begin with, but i didn't look at them carefully in the shop and when i brought them home 3 of them had really bad whitespot. after medicating them etc 5 of them became too weak and stressed to continue so they died. now only one is left... :( might get a few more when i'm ready for them or i might just give away the one i have because he is really big now.
 
my guess is the pellets are just a coincidence. your oscar is growing up, and most of them become very territorial - even to fish they were friendly with before.
 
How big is your tank? My oscar sometimes sees his reflection in the side of the aquarium and he tries his hardest to bite and fight it. That could possibly be what your oscar is doing. I've never heard of pellets making a fish aggressive. Live food, space and competition are what usually causes certain cichlids to become aggressive.
 
well right now my oscar is in a 400L tank by himself. he has never been aggressive before so i'm guessing he's just growing up...teenager hormones and all LOL...
 
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