on glass means death is near, but why?

[fishtales]

hi,
i am sorry my first two posts have been about a tough subject.

every large pleco i ever had(that passed away) did not suck on the glass during it's life. then one day they all did. they would do this for a few days to several weeks(including the one in my first post here). even with the lights on. then that would be the end. i have discussed this with a number of people that keep them and they have not ever ever seen this happen.

i was wondering if anyone else has witnessed this and what may be the cause. when this is observed is there any way to help them? currently everything is ok. i am just asking this since i joined this board and i seem to be unique as to witnessing this.

thank you

main tank info:
200 gallon. constant water exchange through ro,di,uv,carbon. sump run with bio balls,eheim canister. trace elements readded. vac every 3 days. ph 6.0,amonia 0,nitrites 0, nitrates less than 5,phosphates 0,silicates 0, dh and kh are opitmal(softer) but i cannot remember the last test numbers right now. temp 85 f regulated,60 watts cfl 5 hours per day. plenty of driftwood caves etc. not planted. currently 3 pl*co's(that can live in this water), 3 very large discus,7 tetras,3 curviceps. never overstocked, very little bioload. the fish in the last thread was the first one i had lost in 7 years.

[MatsP]

I have certainly seen fish that are either stressed or ill sit on the glass, when "normally" they wouldn't. I'm not entirely convinced it is "diagnostic" - as in it's not a sure way to determine that they are going to be passing away. But it may be one indicator.

I guess it's a bit like the opposite of a cat, that usually hides somewhere when they don't feel well.

Generally speaking, I'd say that "change in behaviour" is sometimes a sign of illness. But it can also be a sign of breeding or some such...

--
Mats

[fishtales]

thank you for answering. that is the most logical answer i have heard.

you are correct. for instance when i am vacing. i of course pick up their cave etc. for up to a day after that they will suck on the glass sometimes. but do not pass away. they are just bothered. i have had ones that had not been bothered do this out of the blue and that is when they die. i figure it is an indicator that they are stressed or ill as you said. when this occurs i do not know any action that would be taken. since most often you cannot tell what is stressing them. or what illness they may have if there are no other signs. for instance the one that passed two weeks ago was most likely stressed because he was ill. or another fish was bothering him. i have had a couple die with no warning whatsoever as well. they seem not to be like other fish where you would usually see external signs of a problem. for one thing they hide in caves all day. i just always wondered about this. i think you gave the best answer.

[racoll]

There is more oxygen higher up the tank and in the current of the filter.

When fish are ill, often the gills are not working properly, so ill fish need more oxygen - hence getting in places where there is more oxygen/current.

[fishtales]

i thought of that right away. the strange thing is the ones that died were not near the top. the ones that always live and just do it because they are bothered like to hide behind the plumbing or overflow at the top. i think that has more to do with finding another hiding place when they have been hustled out of their cave.

maybe it is like a cat purring. many people think a cat purrs when it is happy. they mainly purr to comfort themselves when they are agitated or ill. maybe sucking on the glass soothes them.