Incompatible Mated Pair? Territorial behavior

Hi All! Recently took in/adopted an alleged breeding pair of blue discus. Size: 5.5" and 6". The bigger of the two was not in the most perfect shape (very obvious stress/vertical bars + cloudy eyes + clamped fins). After 4 days in my care the stress bars on the bigger one are all gone and the eyes have cleared up by 95% and he/she is now stretching his/her fins more and more. As both are slowly getting accustomed to the tank,the bigger of the two has started to show some unwanted behavior however. Some behaviors noted below:

1. The bigger one (he or she, I am unsure) would push the smaller one to the corner. If the smaller one moves, he/she would approach her asap and push her back into that same corner. I can only assume this behavior to be territorial in nature. The tank is 40Gallons, which I believe to sufficient for a "pair".

2. When I feed, the bigger fish would "sometimes" try to swim on top of the smaller one to prevent her/him from eating.

3. To add, during feeding, he would also attempt to peck at the smaller one while trying to eat at the same time, its attempting to scare the smaller one away back to its corner. I have to tong-feed the smaller one to make sure she/he gets enough. Both fishes are aggressive eaters however. During feeding, despite the aggressive behavior displayed by the bigger fish, the smaller fish would still swim to the front of the tank. Feeding sessions are sometimes interrupted when the bigger fish makes it his priority to push the smaller fish back to the corner. After a few minutes when the bickering subsides (usually both fish in same corner doing nothing), I would approach the tank and both would swim to the front of the tank again to get fed again.

4. The bigger fish would guard the smaller fish. If it moves, he tries to peck near the fins or bump the abdomen with its snout. The smaller fish would then go back to his/her corner.

5. The smaller fish developed very faint stress bars, visible only from a certain angle. The bars werent present when I first took the fish in.

6. The smaller fish would semi-fold his/her dorsal fins (i can only liken this to cowering/submissive behavior).

7. The bigger fish would shiver sometimes when its near the smaller fish.

8. Both fishes rest in the same corner, maybe the bigger fish's idea of preventing the smaller fish from swimming around.

9. Have observed both fishes tail slapping each other on day one aggressive behavior started. Now, tail slapping only done by bigger fish.

10. Hard pecking by big fish noted around 10-20 times. Hard enough that it sometimes spook fish to make a dash for it. Its like theyre spooking themselves.

11. 1 Pectoral fin of smaller fish showing some tears now.

12. Both fishes have displayed some body vibrating behavior.

13. Smaller fish initially tried to fight back, but became completely submissive a few days later.



So far, those are some of the behaviors that I can remember. By any chance they are actually not a mated pair and the bigger fish is displaying typical territorial behavior? Do mated pairs display territorial behavior on each other? Any advise would be appreciated! Thank you.

Sometimes pairs divorce. But in you case, it sounds like you have two males and the most dominate one doesn't like the smaller one. Just a guess. Do you have a picture of them that you could post? A pic might help. I don't think that for now, at least they need separate tanks.

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Originally Posted by LizStreithorst

Sometimes pairs divorce. But in you case, it sounds like you have two males and the most dominate one doesn't like the smaller one. Just a guess. Do you have a picture of them that you could post? A pic might help. I don't think that for now, at least they need separate tanks.

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Hello,

Thanks for the reply. Adding pic. Left is bigger fish. Right is smaller fish. The breeding tube looks similar on both fishes. Is breeding tube sexing 100% accurate? I think I came upon a thread here somewhere where the fishes were sexed as both females after tube inspection but ended up having wrigglers. I will have to observe the behavior of the fishes some more. If they are a pair will the fighting stop soon? But if dominating behavior persists for a week or so, from dawn till dusk, is it safe to assume they are not a pair? The bigger one is bullying the smaller fish from sunrise until I turn off the lights for the night. Thankfully the small fish hasn't darkened yet, and eats well. Its also the more beautiful of the two in shape and clarity of pattern. Thank you.

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