bad couples… alpha female is too bossy… I don’t think I’m going to get out of this one…

[Magnum Man39 153]

Silver dollar tank… the dollars I had, had all been raised in different tanks, so this is kind of an arranged marriage, with a pair of common silver dollars… it’s a case of she wants a man, but she is too bossy for his tastes… they had kind of nested, but she would throw temper tantrums when he didn’t suit her… so he moved out… now he sits in an upper corner of the tank, and is not eating… there are 5 other dollars of various ages in the tank, that appear to act in a social structure… she goes into his corner occasionally, and appears to try to coax him out, but he doesn’t move… I’ve moved him using the magnetic algae scraper in the tank, a few times, but he ends up going back to the same corner, as soon as I quit harassing him… I have one adult spotted dollar in another tank, that was a companion for my angel fish that recently passed, I’ll be moving it ( not sure of the sex of that one, but suspect it’s female ) that will shake up the dynamic, and hopefully he joins the group again…he was a healthy well fed adult male… not sure how long he can hold out his hunger strike, but it’s been over 2 weeks since I’ve seen him eat anything… he may be sneaking nibbles off the roots, but has not eaten any of the offered foods , which he ate previously… he does have a “digger” on his nose, likely the result of bashing something… maybe he is just embarrassed, as he was physically perfect previously… the abrasion is not such that it should impede his eating… thoughts???

 

[Magnum Man39 153]

he is in the upper left of this picture… and she is center bottom

 

[Magnum Man39 153]

this is a close up of his injury… I don’t think it’s a disease, I think he bashed something, when they were fighting, and he was flying back and forth across the tank…

 

[Magnum Man39 153]

for the most part they all get along… the smallest ( a tiger ) is about the size of an actual silver silver dollar… the problem seems to be between the adult male and female commons

 

[Magnum Man39 153]

BTW… the new to me red hooks are interesting, their eyes are larger, and fins longer than I noticed in on line pictures…

these dollars are all being groomed for the 250 gallon, when it’s ready..

 

[Magnum Man39 153]

he’s starting to relax from the top corner a little, tomorrow a water change, and adding the spotted dollar…
a better picture of the red hooks… these guys are about 1/2 mature size…

 

[SammyTargo]

I used to own spotted silver dollars, but you have red hooks. They still behave similarly, so I can probably help out here.

From what I see, this is probably the case:

1) Social Hierarchy Stress
Silver dollars are schooling fish with loose dominance hierarchies, so when you mix individuals raised separately (“arranged marriage”), they have to establish rank, test the boundaries, and form their own subgroups.

Your seeing that the:
Female = dominant/aggressive
Male = subordinate → chronic stress response

From my experience, the “corner sitting” is textbook withdrawal behaviour, energy conservation, and will to avoid any confrontation with the others. The fish got psychologically pushed out, therefore it may stop eating entirely.

2) Failed pairing stress
Even though silver dollars sometimes pair, they’re not like cichlids that form strong bonds. She wants interaction, and he doesn't respond correctly. It's normally the result of social pressure in schooling fish.

The injury you saw was probably from glass surfing or fleeing aggression, and it could very well lead to:

• Infection
• Discomfort while grazing
• Increased stress hormones

Because of all of this, adding the spotted dollar might help—but it could also increase competition, reinforce hierarchy, or stress him further.

What I would do:
1.
Separate or isolate by putting the male in a breeder box inside the tank or a separate recovery tank.

2. Lower stress in the main tank
If separation isn’t possible, add visual barriers (plants, driftwood), dim lighting, increase cover near his corner. However, the photos of your tank show that there is ample coverage so this may not be very effective.

3. Target feeding
Try highly tempting foods like blanched zucchini / spinach, soft pellets soaked in garlic, or bloodworms (even though they’re herb-leaning fish, they’ll take them when stressed). Try to feed near his corner, not in open water.

4. Monitor the wound

If symptoms for fungal or bacterial infections show up, treatment should be applicated. This is simple stuff though, and won't fix the main issue.

5. [Important] Watch breathing and posture
Bad signs:

• Rapid gill movement
• Clamped fins
• Tilting

If those appear than this is no longer just social stress.

Let me know what happens! Good luck...

 

[Magnum Man39 153]

so, this update a little more than a month later … that male dollar is still mostly up on his corner at most times… but does move around a little… yesterday was the 1st time I saw him take an algae cookie ( these are their favorites ) or any of the offered foods… he almost has to be eating pothos roots, or he surely would have starved in over a month of not eating any thing…

they all eat the pothos roots, and the band was put together to naturally take control of the previously out of control pothos roots in this tank… they are getting ahead of them…

I haven’t taken the time needed to deconstruct the tetra tank, that would be needed to catch the spotted dollar out of that tank yet, so that hasn’t changed yet…

but at least I’ve seen the big male eating again…

 

[TwoTankAmin32]

In my experience fish behave in the way you describe for one of two reasons which can both be present together or on their own.

1. The fish is sick. The result is it feels poorly, may know it cannot manage any confrontation and it secretes itself as a result. It may even be reluctant to participate in the usual feeding frenzy that often occurs in a tank when the food goes in. Basically, it goes into hiding. We can tell if it is not eating over time as it will lose body mass which we can see is happening.

2. The fish is being picked on. This may or may not have resulted in it being injured which can make it feel similar to being sick. But, without being injured it may still want to avoid further confrontation at any cost. The only chance it has to do this is to go into hiding.

In both the above cases things can change for a number of reasons. A sick or injured fish can recover. But, it also can get worse and even die. However, we can also change things for the fish by treating one which is sick or injured. This may require an H tank. Also, we might be able to move a fish which is not sick or injured but is being beaten up to a different tank. If we don't have one, we may be able to give it to somebody who can help by taking it. But they need to know the whole situation beforehand.

(edited for 2 typos)