My Bluegills Got Shy!

I have three bluegills (about 4 inches) which for the last 15 months have been very agressive eaters - they would take krill from my hand. For the past few weeks they have been extremely shy - won't eat much and almost nothing if I'm anywhere near the tank. I think something is wrong with them. I can't see anything physically wrong with them - they are active - and I change 20% of the water each week and keep the filter clean. The ammonia levels are nearly zero. Is there anything else I can do? Any other tests?


Cheers,
Ken

Does their tank receive direct sunlight at any time during the day? Sunlight patterns this time of year are different from summer patterns. This pertains to a pet theory of mine...

Multiple possibilities:
1) I used to do feeding trials with individually housed bluegill and black basses where feed intake was tracked. Usually a given individual would feed very well for weeks or days and then abruptly stop for a couple days before resuming the higher rate of intake. I worked with 24 or more individuals at a time so average feed intake was not low but if you are working with a smaller number like three, it is more likely than I observed to have all three go off feed at same time. Reaseon for going off feed under those conditions unknown since I controlled temperature and photoperiod.
2) You feed is going bad or low in critical nutrients even when fresh. Some hypo-nutrient levels (a nutrient too low), especially with the lipid soluble vitamins (A, D, E and K), are slow to promote signs such as depressed appetite. Try a fresh feed or another type of feed. If they eat the nutritionally complete diet their appetite usually will return after a couple days. In my experience krill is not a good staple as I associate it with whole in the head and abnormal scale development. It can still be used as a treat.
3) Someone or something chasing or scaring fish when you are not around?
4) You write nothing about temperature, so try bumping it up.
5) Do they scratch themselves or hold their fins clamped most of the time?

I have three bluegills (about 4 inches) which for the last 15 months have been very agressive eaters - they would take krill from my hand. For the past few weeks they have been extremely shy - won't eat much and almost nothing if I'm anywhere near the tank.

Someone or something chasing or scaring fish when you are not around?

That would be my fisrt guess, but incase it isn't that. How big is your tank, and how much have they grown over the past 15 months to get to 4 inches? The behavior you described reminds me of some gold severums I used to have. I bought them small ~ 1 inch and kept them in a 38 gallon tank (total of 3 but 1 severum in the tank at a time). Each of them was fine when small but as they approached palm size, became increasingly skittish. I lived alone, and all the other fishes were less than half the size of the severums and stayed out of their way so no one / nothing was scaring / chasing them. I came to believe that they felt confined as they grew and this made them nervous. If your fish have grown a lot and are in a smaller tank, perhaps this is what is happening.
Just to be sure I'm understanding the problem correctly, do they seem frightened of you? Try to hide etc... when you are near or are they just unwilling to eat?

Edited by smilingfrog, 15 November 2008 - 05:26 PM.

Thanks for the suggestions, folks.

1) My tank doesn't get direct sunlight at all and due to a timer-driven tank light, the hours are pretty regular.

2) There isn't much to disturb the fish, unless my wife secretly hates them. No kids, no cat, etc. However, the apartment next door is being renovated and the noise has occasionally been intrusive... it could be a factor, as the fish run to cover when our nearby washing machine is on.

3) I bought extra large containers of blood worms and krill on the cheap, so they've lasted longer but they could very well be stale. It could be a factor. I'll try some fresh food... i suspect searching this forum will give me some brands for a good, balanced staple...

4) The fish don't keep their fins clamped... they open and close them regularly. They enforce a pecking order (fairly tame these days). I have seen one of them scratch on driftwood once or twice recently. What might this suggest?

5) I don't heat the tank, so it has been cooler lately. But, I didn't notice this condition last winter. Maybe I'll raise our thermostat!

6) The fish seem frightened of me, to the point of not feeding. They are waiting to eat in the morning but my (gently) raising the lid causes them to scurry for cover. When they do feed, they zip up, grab a bite and zip back. Before, they were darn near attacked me at feeding time.

7) The fish have grown an inch or less since I've had them. I've tried to feed them in moderation, as they will likely outgrow my tank (only 25 gallons) and I'm not able to get a larger tank any time soon. Poor planning on my part... unfortunately, I didn't find this website until AFTER I captured the fish.

I've got some things to try now. Much appreciated!

Cheers,
Ken

4) The fish don't keep their fins clamped... they open and close them regularly. They enforce a pecking order (fairly tame these days). I have seen one of them scratch on driftwood once or twice recently. What might this suggest?

Occasional scratching (flashing) not a major concern. Just means they got an itch although a parasite maybe involved. Parasites loads heavy enough to limit feeding usually result in listless behavior and more frequent flashing.

Temperature drop does cause a qualitative change in behavior. At higher temperatures my fish do hang at the surface hit everything including me. As temperatures drop into the low seventies and below they loose their confidence and hit feed with a burst from cover. I think they are hardwired to avoid lingering at the surface when their reaction time increases as temperature drops making them less capable of avoiding warm blooed predators such as birds. My bluegill in ponds clearly show the patten of no longer loitering at surface when water is cool.

Update - my bluegills have been slowly regaining confidence and are eating better.

1. The noisy construction next door has ended
2. I've made more shelter by rearranging the tank and adding more live plants.
3. I've purchased new dried blood worms and added some live food to their diet. Sadly, they refused Hikari sinking carnivore pellets and shrimp pellets I would like to find another dried food for variety and a more balanced diet.

Thanks to all...

You said your ammonia levels are nearly zero...they should be at zero. If there is any detectable ammonia (or nitrite) then I would say that is the problem.

Update - my bluegills have been slowly regaining confidence and are eating better.

1. The noisy construction next door has ended
2. I've made more shelter by rearranging the tank and adding more live plants.
3. I've purchased new dried blood worms and added some live food to their diet. Sadly, they refused Hikari sinking carnivore pellets and shrimp pellets I would like to find another dried food for variety and a more balanced diet.

Thanks to all...

DO not be so quick to give up on a pelleted diet. Sometimes it takes repeated exposure (many times).

DO not be so quick to give up on a pelleted diet. Sometimes it takes repeated exposure (many times).

The fish only have a couple of seconds to try them before the sinking pellets disappear in the pebbles.... more nutrient load, just what I needed. If I can find a floating pellet, I'll try more. Can you recommend anything?

The fish only have a couple of seconds to try them before the sinking pellets disappear in the pebbles.... more nutrient load, just what I needed. If I can find a floating pellet, I'll try more. Can you recommend anything?

Many feed brands come as sinking and floating options. Look at label. Feeds with large amounts of shrimp / krill meal tend to be highly palatable. Ohterwise make certain the feed offered is from a freshly opened freshly manufactured container.