Cross contamination and parasites

[MissPH]

Hi all,

I have recently acquired a nocturnal species of octopus (Starry Night octo) and am trying to establish a regular feeding routine for him. His mantle is currently approx 1.5-2" and arms approx 6-7". I have had him 2 weeks now in a 120 gallon tank. Early on (between about 5-8 days) he interacted a fair bit but he has become more reclusive since.

So far I have not actually seen him feed - he doesn't seem to like doing it while I am around - even with tank lights off - but I have left offerings of frozen thawed mussels which have sometimes disappeared overnight (assuming he has taken them as there isn't much else in the tank to eat it). I have tried him with frozen thawed krill but he hasn't touched them. I tried putting food in a glass bottle to make it more interesting but all that did was trap a small crab (which he also ignored!). I know he has killed and eaten a crab bigger than his own size in the tank as I have removed bits of its body I found lying about. I tried him with a feeding stick once with mussel and he just gently touched it with 2 tentacles then slinked off and hid for a good few hours.

The problem I have is I can't seem to get him into a regular feeding routine, and he doesn't seem to be overly enthusiastic about the food I am offering (often leaves it untouched overnight) I wanted to get him on a diet primarily of thawed frozen but with a few live crabs/shrimp thrown in as treats every now and again. I would like to incorporate more live into his diet at this early point to get a routine going at least.

A big stumbling block for me here is that I am from the UK and do not live near the coast, therefore sourcing live crabs and marine shrimp is difficult. When it is warmer I could easily source live bait peeler crabs from our shores however I have been warned of the risk that UK shore crabs may carry parasites which the octopus is not familiar with and therefore can't fight off. Does anybody have any experience or knowledge about this potential issue?

One option I have been taking advantage of is mooching live crabs which have hitched a ride with shipments of live rock from the aquarium I bought the octopus from. Normally they just throw these crabs into the sumps of their display tanks so are happy to let me have them instead. However this isn't a reliable source and often the crabs are really tiny. I sometimes get lucky but not every time.

Another option is buying live shrimp, although I am having trouble finding saltwater shrimp. River shrimp is no problem to source and cheap but I am concerned they will die from osmotic shock before they are eaten and start rotting. The supplier assures me that the shrimp are kept in brackish water and so would live indefinitely in a saltwater tank but I am sceptical.. I am less worried about cross-contamination with shrimp as they are captive bred. I think brine shrimp will be too small for him.

Any comments or advice would be much appreciated! Thanks

 

[DWhatley]

I mentioned this feeding list in your other post but will include the reference here for others searching for similar answers. Most of the food can be sources from a seafood market or Asian grocery if they are common in the UK. Most US cities have at least one local Asian market and most of our groceries some kind of seafood department but almost all foods were frozen at some point in the food delivery chain even if they are purchased as fresh.

Brine shrimp are worthless food even if (yes they are too small) Orion would eat them, avoid!

Since he has eaten a crab, I would focus on finding crabs until he is eating well. If you try table shrimp (second best food) make the initial piece eye sized and offer on a stick, touching the suckers as close to the mouth as you can get without poking him.

One cautionary note, his gyrations on the tank wall, daylight activity and resistance to eating may be signs of senescence. As I mentioned, we have not classified this animal as luteus in the past because it is far smaller than the only semi-official (Mark Norman's Cephalopods A World Guide) description easily found for Octopus luteus (the Callistoctopus is a newer Genus classification - there have been several in the last 5 years - and I am not sure where the break from Macropus is now delineated). There is a smaller Macropus marked sp (undefined species) that better fits the size. Note that there are many commonly known octopuses that are not officially described or appear similar to others and get lumped into the same common name.

Parasites are also an area of the unknown. Octopuses do not carry the normal marine parasites that we see on many scaled fish but others have been found in necropsy to harbor in their gills. Impacts of parasites are not well studied and we have no recommended treatments or ways to determine an infestation. Bacterial infections are more of an identified concern and are seen in the eyes and skin. Avoiding wounds by keeping species only tanks, limiting corals to extremely low sting animals and as a last resort adding tetracycline (there are a few others) to food when infection is observed have been our methods to control infection problems.

 

[DWhatley]

My Google scan just happened to produce a new article on octopus parasites. It is of little use to the hobbyist but the abstract emphasizes my comment about how little we know about parasites in cephalopods and how they react.