In reply to a recent enquiry, what exactly is 'the Aquarium of Vulcan' from which this blog is named, its useful to refer to the ancient Greek literary figure of Athenaeus, author of the Deipnsophistae or 'Banquet of the Philosophers' the allusive source of the little-known myth of Vulcan's love-gift to Venus.
But first, by far the better-known myth associated with Vulcan is that of the goddess Venus caught in bed with Mars, trapped by her husband Vulcan throwing an 'invisible net' over the pair of lovers. The Roman poet Ovid supplied rich material for many Renaissance-era artists in his Metamorphoses including a description of how Vulcan responded when discovering Venus and Mars in bed together.
'At once, he began to to fashion slender bronze chains, nets and snares which the eye could not see. The thinnest threads spun on the loom, or cobwebs hanging from rafters are no finer than was that workmanship. Moreover, he made them so that they would yield to the lightest touch, and to the smallest movement. These he set skillfully around his bed.
When his wife and her lover lay down together upon that couch they were caught by the chains, ingeniously fastened there by her husband's skill, and they were held fast in the very act of embracing. Immediately, Vulcan flung open the ivory doors, and admitted the gods. There lay Venus and Mars, close bound together, a shameful sight. The gods were highly amused; ... They laughed aloud, and for long this was the best-known story in heaven'. 
Vulcan enmeshing Venus and Mars in his net was a popular subject for many Renaissance artists including Velasquez, Tintoretto, Piero di Cosimo, Van Dyck and Rubens. Northern Mannerists artists in particular, such as Wtewael, Spranger and Heemskercke were all attracted to the myth.
Tintoretto in his 'Mars and Venus Surprised by Vulcan' dated 1551-1552 (below) has Vulcan interrupting Venus and Mar's love-making without his net. Examining by invitation her beauty, in close proximity, Vulcan is momentarily distracted from detecting a seemingly timorous Mars hiding under a bed.
The Dutch Northern Mannerist artist Joachim Wtewael (1566–1638) painted the moment in which Venus and Mars are surprised by Vulcan in three differing versions (below). The main protagonists of the celestial drama with their respective attributes can all be seen in Wtewael's elaborate staging, including Mercury with his caduceus, Saturn with his scythe along with Vulcan preparing to fling his net over the lovers.
Bartholomew Spranger (1546-1611) was a Flemish artist who worked as a Court artist for the Holy Roman Emperor Rudolf II. The erotic content of his 'Vulcan and Venus' (below) is overt with its emphasis upon the Beauty and the Beast aspect of the relationship. The art critic Linda Murray notes of the main thematic and stylist traits of Mannerist art -
'Mannerism can be quite easily recognised and defined: in general it is equated with a concentration on the nude, often in bizarre and convoluted poses, and with exaggerated muscular development; with subject matter either deliberately obscure, or treated so that it becomes difficult to understand -the main incident pushed into the background or swamped with irrelevant figures serving as excuses for displays of virtuosity in figure painting; with extremes of perspective, distorted proportions or scale -figures jammed into too small a space so that one has the impression that any movement would burst the confines of the picture space; with vivid colour schemes, employing discordant contrasts, effects of 'shot' colour, not for descriptive or naturalistic purposes, but as a powerful adjunct to the emotional impact of the picture'. 
Its a seemingly unequal pairing of a submissive Vulcan and dominant Venus in Spranger's interpretation of the two gods relationship.
The Graeco-Roman myth of Mars trapped by Vulcan's net is included in the hermetic phantasmagoria of the English physician-philosopher Thomas Browne's 'network' discourse, The Garden of Cyrus (1658) its full running title being The Garden of Cyrus, or the Quincuncial Lozenge, or Network Plantations of the Ancients, Naturally, Artificially, Mystically considered.
'As for that famous network of Vulcan, which enclosed Mars and Venus, and caused that inextinguishable laugh in heaven; since the gods themselves could not discern it, we shall not pry into it. Although why Vulcan bound them, Neptune loosed them, and Apollo should first discover them, might afford no vulgar mythology'.
And in fact the highly symbolic figure of Vulcan opens Browne's hermetic discourse, ('That Vulcan gave arrows to Apollo and Diana') and ushers its apotheosis in which 'Vulcan and his whole forge sweat to work out Achilles his armour'.
On a mundane level the appeal of the myth of Venus and Mars surprised by Vulcan may be viewed as social commentary upon the rise of adultery in urban Europe. During the Renaissance, with the increase and mix of population in European cities, opportunities for extra-marital affairs grew. The myth served well as a moral warning to its viewers. Renaissance painters also seized upon the myth of Venus and Mars and its symbolism in order to comment upon war-torn Europe of the late 16th and early 17th centuries for from the union of Venus, the goddess of Peace and Mars, the god of war, a child named Harmony was born. From an esoteric perspective the union of Venus and Mars is a lesser example of the 'coniunctio' or union of opposites in alchemy which was more often symbolized by the luminaries Sol et Luna.
Although Vulcan was famed for his inventiveness, making armour for the hero Achilles and a chair for his mother-in-law from which she could not escape when sitting on, no painting has survived of his constructing an aquarium for Venus. In any event, Casaubon's edition of Athenaeus's 'Banquet of the Philosophers' was not published until 1612 and therefore no painting of this subject before this date is possible. There is however at least one Renaissance painting in which Venus is depicted visiting her husband Vulcan's forge, perhaps for the purpose of requesting a love-gift.
In the Dutch painter Jan van Kessel's 'Venus at the forge of Vulcan' of 1662 (below) the stark contrast between the naked vulnerability of Venus and the metallic accoutrements of protective armour scattered in its foreground is notable.
Thomas Browne for one knew that a close relationship existed between the goddess Venus, water and fish. In his commonplace notebooks the following verse couplet can be found-
'Who will not commend the wit of Astrology ?
Venus born of the sea hath her exaltation in Pisces'.
Its possible that Thomas Browne knew of the myth of Vulcan's Aquarium for Isaac Casaubon's 1612 edition of Athenaeus's Deipnosophistae, or 'The Banquet of the Philosophers' is listed as once in his library. Browne also wrote a short, humorous piece entitled 'From a reading of Athenaeus'. 
Athenaeus lived in Naucratis circa the late 2nd to early 3rd century CE In his day Naucratis was an important Egyptian harbor and a dynamic melting-pot of Greek and Egyptian art and culture. Its also the setting of 'The Banquet of the Philosophers' in which characters such as physicians, philosophers, grammarians, parasites and musicians discuss topics as diverse as Baths, Wine, invented words, feasts and music, useless philosophers, precious metals, flatterers, gluttony and drunkenness, hedonism and obesity, women and love, mistresses and courtesans, the cooking of fish and cuisine in general, ships, entertainment, luxury and perfumes.
In total the 15 books of the 'Banquet of the philosophers', mention almost 800 authors. Over 2500 separate works are cited in it, making it a valuable source of numerous works of Greek literature which otherwise would have been lost, which includes three surviving lines on Vulcan's aquarium.
James Russell Lowell famously characterized the Deipnosophistae as -'the somewhat greasy heap of a literary rag-and-bone-picker like Athenaeus is turned to gold by time'. In the seventeenth century there was a revived interest in the Banquet of the Philosophers following its publication by the scholar Isaac Casaubon (1559-1614) in 1612. The commentary to the text was Isaac Causabon’s magnum opus. Incidentally it was the scholarship of Isaac Causabon which proved from his textual analysis of the Corpus Hermeticum that it could not have been written by the mythic ancient Egyptian Hermes Trismegistus who anticipated the coming of Christ, as commonly believed, but in fact was a syncretic work of Gnostic and Greek philosophy dated centuries after Christ's era, circa 200 and 300 CE.
By all accounts Athenaeus was a favourite author of Thomas Browne for he stated in his encyclopaedic endeavour Pseudodoxia Epidemica-
'Athenæus, a delectable Author, very various, and justly stiled by Casaubon, Græcorum Plinius (Greek Pliny) . There is extant of his, a famous Piece, under the name of Deipnosophista, or Coena Sapientum, containing the Discourse of many learned men, at a Feast provided by Laurentius. It is a laborious Collection out of many Authors, and some whereof are mentioned nowhere else. It containeth strange and singular relations, not without some spice or sprinkling of all Learning. The Author was probably a better Grammarian then Philosopher, dealing but hardly with Aristotle and Plato, and betrayeth himself much in his Chapter De Curiositate Aristotelis. In brief, he is an Author of excellent use, and may with discretion be read unto great advantage: 
Its in book 2 of 'Banquet of the Philosophers' that Athenaeus records how the blacksmith of the gods Vulcan set about creating sheets of glass which he bonded together with an early version of tungsten steel. Tungsten is one of the oldest elements used for alloying steel. It forms a very hard carbide and iron tungstite. High tungsten content in the alloy however tends to cause brittleness and makes it subject to fracturing rather than bending. Somehow Vulcan over came this weakness, its speculated through adding 'the salty sweat' of his workshop labourers to the molten crucible.
The little-known myth is recounted in the Deipnosophistae after heated discussion upon the best sauces to prepare for fish. The courtesan and lute-player musician Callipygae recites three verses from a long-lost comedy, now known only by the title of The Chessmen of Odysseus. Its believed that the following lines specifically allude to Vulcan's aquarium -
As the Pleiades ascended, Vulcan's workshop laboured,
the sound of hammer on anvil could be heard
echoing through mountains
until rosy dawn glowed furnace-like in the east.
Salty sweat streamed in torrents into hissing troughs,
smelting and refining the dross.
Crafted and ready
to bind with ox-like ribs the thick and cloudy glass,
Vulcan's love-gift for Venus.
 (Book 2 Lines 27-29 )
Aquariums are mysterious habitats which often evoke great underwater beauty. They function well as calming distractions, their psychological benefits include reducing stress and anxiety. Looking into an aquarium, observing fish swimming care-free, helps people momentarily forget their worries. The symbol of an aquarium invites speculation and analysis. For the seminal twentieth century psychologist C.G. Jung -
'The protean mythologem and the shimmering symbol express the processes of the psyche far more trenchantly than, in the end, far more clearly than the clearest concept.' 
Perhaps Venus made her request to test the fullness of Vulcan's forgiveness, or else to alleviate her boredom with Vulcan spending long hours away from her at the forge, or simply for her amusement and pleasure, its not really known. Nor is it known how many or what kind of fish she choose to place in her aquarium. But whether Vulcan manufactured his love-gift for Venus specifically for any of these reasons remains unclear. What is clear is that the fish in the Aquarium of Vulcan are far more playful than previously imagined.
 Ovid Metamorphosis Book 4 lines 180-190
 The High Renaissance and Mannerism Linda Murray Thames and Hudson 1977
 1711 Sales Auction Catalogue page 7 no. 67
 Pseudodoxia Epidemica . Bk.1 chapter 8
 Deipnosophistae Book 2 lines 27-29
 Collected Works of C.G.Jung vol. 13 Alchemical Studies (1967) para. 199