Endler Looks Bad

[Mickfender]

Hi looking for a bit of advice as 1 of my endlers looks like he's dying. Ive got a fluval 125 ltr tank with tetratec ex700 filter. The tank was cycled before any fish went in for about 4 months. I added 6 endlers 3 male 3 female i bought on e-bay about 2 months ago,at the same time 6 young sterbai cory. A week after this 3 endler fry where born all female. A month later i added 8 serpea tetra, my water i check weekly is always 0 ammonia 0 nitrite and about 40ppm nitrate, it comes out of the tap at about 20-30. Everything has been going fine no problems,also my tank has quite a few plants that have been growing fine. On sunday i added 6 baby albino sterbai, the girl in shop said they where about 4 months old and they are quite small, they seemed fine all over the tank except 1 that was hiding all the time, Tuesday 1 albino dead i think it was the 1 that was hiding as it was a bit smaller than the rest,i bought another from same batch at shop. These all seem fine the 6 sticking together nobody hiding, then now weds evening 1 of my male endlers is struggling on the btm of tank only moving a few cms over sand if something goes near him, now he has limped behind wood and plants at back of tank and cant be seen,everything else seems ok, but he looks like he on the way out, sorry for the big long post but thats the background of tank. What i wanted to know does this sound like a fish dying of old age as i dont know how old he was when i got him and endlers are not very long lived. There is nothing visibly wrong with him no marks or bits missing just looks like hes not going to live for much longer, Thanks Mick

 

[Mickfender]

Just checked, hes dead he had the back part of his tail missing, dont know if that was me trying to get him out as he was in awkward spot,or if some other fish done it, but his tail was ok as i got a good look at him when he was at front of tank. Mick

 

[OldMan47]

You have several factors at work Mick. First is that the perfect water for the sterbai and the serpae tetras would be completely inappropriate water for endlers. Those fish will thrive in water with very low mineral content and a pH of 7.0 or a bit less. The endlers will thrive in hard water having a high pH and a high mineral content. Another factor working against your success is that endlers are fairly short lived. That means that an endler colony with no breeding and fry drops going on will dwindle away to nothing in about a year. With the serpae tetras, it is unlikely that many endler fry are surviving to replace your losses in your tank, so the endler numbers will decrease. The sterbai cories are not a threat to endler fry but the tetras definitely are.
My own endler colonies produce so many fry that a single male or female going missing after 6 months would not even be noticed. At 6 months after I got my first 4 pairs of endlers, I had a 45 gallon tank bursting at the seams with well over 100 endlers. A big difference between my situation and yours is that I had only endlers and cories in my tank at the time. Endlers almost ignore their fry and cories are not a threat to any healthy livebearer fry, not even my tiny Heterandria formosa fry.
As far as the water, do you know what the characteristics of your tap water are? Maybe that would give us some insight.

 

[Mickfender]

Thanks for the reply oldman47, my tap water is about 30-40 ppm nitrate and ph of 7.6. When i check tank water the ph is 7.8 and before a water change of which i do about 35% per week the nitrates are 40-60 hard to tell but i allways think its closer to 40 really.