Garden Eel Woes

[Ambientshdw]

Hey Everyone,

I have been taking care of a spotted garden eel tank, and recently have been having issues. The tank is connected to a few other tanks as part of a walled display.

Facts
System volume: 300 gallons
System flow rate: 14x turnover per hour.
Garden Eel tank: 75 gallons
System/tank age: 2+ years
Filter socks: changed once daily (on from 10 am - 6 pm)
Skimmer: Yes
Sump: Carbon changed bi-weekly, matrix
Sandbed: 6-8"
Tank inhabitants: 13 garden eels, 1 CB butterfly, soft coral
Feeding Schedule: mysis/spirulina brine 3x daily

The tank has been running spectacularly until recently. The garden eels appear to have just disappeared, no trace. Not finding them in the sump, filter socks, or in the sand. If they are dying in the exhibit, it is in the sand.

No other animals on the system have been affected. So I believe the issue is localized in this specific tank. The sand bed has not been disturbed much over the last two years, other than agitating diatoms off the surface. I would expect it to be anoxic, but that is their natural habitat correct?

If anyone has any advice or theories they would be deeply appriciated.

[Theoj]

i can't really comment about the whereabouts of the garden eels I'm afraid however 13 garden eels in a 75 is very very heavily stocked imo, even though its connected to a 300g system. have you actually physically checked in the sand? if not id advise saying to gently go though it with a tooth brush but try not to disturb the sanded too much if thats possible. in addition, have you checked the exterior incase they've jumped?

[Ambientshdw]

The top is completely covered with a custom window/screen top. It is impossible for anything to jump out.

Water Perimeters:

Temp: 72 - 74
Salinity: 1.023-1.025
pH: 8.2
Ammonia: 0
Nitrite: 0
Nitrate: 10-15

[Theoj]

how deep is ur sand bed?

[Megistos]

How long have they been gone?

Like said above, try gently checking your sand bed. Failing that, check your overflow.

[billsreef]

How long have those eels been in the tank?

[Ambientshdw]

how deep is ur sand bed?

The sandbed is ~8 inches deep.

How long have they been gone?

Like said above, try gently checking your sand bed. Failing that, check your overflow.

Garden eel sightings have been decreasing over the past 4 weeks. Historically all garden eels would come out of the sand for their three daily feedings. Lately they have just vanished. The tank isn't new, and they cannot jump out.

During the day a filter sock is on the tank, and is checked every time it is removed. There is no place in the sump for them to hide if they were able to get through the overflow at night, and it is impossible for them to enter the return pump due to screening.

The sandbed has been thoroughly checked, without completely tearing it apart. Typically, the garden eels have small holes that are kept open even when they are hiding in the sand, and even those have not been observed.

How long have those eels been in the tank?

The eels have been in this tank for two years. Recently a few more had been added to replace the missing eels. They have also shown the 'disappearing behavior/not exiting sand'. This leads me to believe this issue is either environmental or something is specifically affecting only the garden eels because nothing else has been affected.

[billsreef]

Are fish added to this system quarantined before addition? And have there been any additions of any livestock to this system (not just the eel tank) recently?

[JoelA7]

Could there be a large predatory worm?

[Theoj]

christ, if there is a worm that big in this world so eat several garden eels with no trace :hmm2: …. i'm done…… just done….. id never put my hand in that tank again :eek2:

[Betta132]

But it would be an AWESOME WORM. If you do find one that big, keep it in a tank of its own!

Hmm... perhaps put a large piece of shrimp on the sandbed and see if anything eats it?